Clinton basks in glow of women senators -- with 1 absence

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13 Women Senators Endorse Hillary Clinton


WASHINGTON -- There were 13 chairs lined up on stage behind Hillary Clinton's podium here Monday night, one for each Democratic woman in the Senate -- except one. The notable no-show was Massachusetts Sen. Elizabeth Warren, the progressive icon whom liberal groups spent more than $1 million trying to draft into the 2016 presidential race against Clinton this year.

The stage setting was emblematic of Clinton's campaign, which has managed to round up the vast majority of the Democratic Party's elected officials into her camp, and especially colleagues of her top rival for the nomination, Sen. Bernie Sanders (who underwent hernia surgery Monday). The 13 women had already endorsed Clinton, along with most of the Democrats in the House.

Look back through Elizabeth Warren's career so far:

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Clinton basks in glow of women senators -- with 1 absence
Democratic presidential candidate Sen. Barack Obama D-Ill., left, listens during a roundtable discussion about predatory lending with Ola Horton, center, from Chicago, and Elizabeth Warren, right, the Leo Gottlieb professor of law at Harvard Law School, at the Illinois Institute of Technology in Chicago Wednesday, June 11, 2008. (AP Photo/Alex Brandon)
*** For Matt Apuzzo Story ** Elizabeth Warren, who chairs an oversight committee set up by Congress to oversee the bailout, is interviewed by the Associated Press in Washington, Thursday, Dec. 18, 2008. (AP Photo/Charles Dharapak)
Neil M. Barofsky, Special Inspector General for the Troubled Asset Relief Program (TARP), moves behind Elizabeth Warren, chair of the Congressional Oversight Panel, on Capitol Hill in Washington, Tuesday, Feb. 24, 2009, as they waited to testify before a House Financial Services subcommittee hearing. (AP Photo/Susan Walsh)
Congressional Oversight Panel Chair Elizabeth Warren conducts a hearing on the Troubled Assets Relief program (TARP), Wednesday, June 24, 2009, on Capitol Hill in Washington. (AP Photo/Gerald Herbert)
Chair of the Congressional Oversight Panel, Elizabeth Warren, attends the TIME 100 gala celebrating the 100 most influential people, at the Time Warner Center, Tuesday, May 4, 2010 in New York. (AP Photo/Evan Agostini)
Council of Economic Advisers Chair Christina Romer, left, and Congressional Oversight Panel Chair Elizabeth Warren, participate in the Women in Finance Symposium, Monday, March 29, 2010, at the Treasury Department in Washington, (AP Photo/Pablo Martinez Monsivais)
Elizabeth Warren, head of the Congressional Oversight Panel testifies before a Senate Finance Committee hearing to examine the Troubled Asset Relief Program (TARP) on Capitol Hill in Washington, Wednesday, July 21, 2010. (AP Photo/Manuel Balce Ceneta)
President Barack Obama, accompanied by Elizabeth Warren, right, and Treasury Secretary Timothy Geithner, left, announces that Warren will head the Consumer Financial Protection Bureau, Friday, Sept. 17, 2010, during an event in the Rose Garden of the White House in Washington. (AP Photo/Susan Walsh)
Elizabeth Warren, head of the new Consumer Financial Protection Bureau, right, makes opening remarks during a mortgage disclosure forum, Tuesday, Sept. 21, 2010, at the Treasury Department in Washington, From left are, Chanelle Hardy, executive director of the National Urban League Policy Institute, Treasury Secretary Timothy Geithner and Warren. (AP Photo/J. Scott Applewhite)
Consumer Financial Protection Bureau head Elizabeth Warren testifies on Capitol Hill in Washington, Wednesday, March 16, 2011, before the House Financial Institutions and Consumer Credit subcommittee. (AP Photo/Harry Hamburg)
Harvard law professor and consumer advocate Elizabeth Warren shakes hands as she arrives in Lowell, Mass. Tuesday, Oct. 4, 2011 prior to the debate between six Massachusetts Democratic candidates for the U.S. Senate seat held by Republican Scott Brown. (AP Photo/Elise Amendola)
Elizabeth Warren, assistant to the president and special advisor to the secretary of the treasury on the Consumer Financial Protection Bureau, prepares for a series of interviews in the White House briefing room in Washington, Monday, July 18, 2011. (AP Photo/Manuel Balce Ceneta)
FILE - In this June 2, 2012 file photo, Massachusetts Democratic Senate candidate Elizabeth Warren speaks in Springfield, Mass. Liberals have groused about President Barack Obama since he was elected, lamenting a lack of progress on issues they hold dear. Even so, most liberal voters are expected to vote for Obama in November over Republican Mitt Romney. But there's no guarantee that liberals, if they continue to be dissatisfied, will turn out to man phone banks and canvass neighborhoods this fall. His fundraising efforts could also take a hit. Their latest beef: that Obama needs to take the fight to Wall Street, much like Warren, the Democratic Senate nominee in liberal-leaning Massachusetts, who has built a national brand around the us-versus-them rhetoric that took root over the past year in the encampments of the Occupy Wall Street movement. For Obama, taking up the Occupy cause as overtly as that carries risks in the dozen or so competitive states that will determine who wins the White House. (AP Photo/Michael Dwyer, File)
In this May 2, 2012 photo, Democratic candidate for the U.S. Senate Elizabeth Warren faces reporters during a news conference at Liberty Bay Credit Union headquarters, in Braintree, Mass. Warren addressed questions on her claim of Native American heritage. (AP Photo/Steven Senne)
Massachusetts Senate candidate Elizabeth Warren, a Democrat, center, flanked by Massachusetts Gov. Deval Patrick, left, and U.S . Rep. Michael Capuano, waves to the audience during a campaign rally, Saturday Sept. 15, 2012, at Boston University in Boston. (AP Photo/Bizuayehu Tesfaye)
Senate candidate from Massachusetts Elizabeth Warren addresses the Democratic National Convention in Charlotte, N.C., on Wednesday, Sept. 5, 2012. (AP Photo/J. Scott Applewhite)
President Barack Obama waves to supporters as he hugs Massachusetts senatorial candidate Elizabeth Warren before addressing supporters during a campaign fundraiser at Symphony Hall in Boston, Monday, June 25, 2012. (AP Photo/Stephan Savoia)
Democratic Senate Candidate Elizabeth Warren, right, speaks to reporters, as Boston Mayor Tom Menino, left, looks on during a campaign event in Charlestown, Mass., Friday, Oct. 5, 2012. (AP Photo/Josh Reynolds)
Democratic U.S. Senate candidate Elizabeth Warren speaks while U.S. Rep. Ed Markey, D-Mass., right, looks on during a campaign stop at a senior center in Medford, Mass., Wednesday, Oct. 3, 2012. (AP Photo/Michael Dwyer)
Democratic U.S. Senate candidate Elizabeth Warren is applauded by U.S. Sen. John Kerry, D-Mass., at a campaign event in Somerville, Mass. Monday, Sept. 24, 2012 where Kerry endorsed her candidacy for the Senate seat occupied by incumbent Republican U.S. Sen. Scott Brown. (AP Photo/Elise Amendola)
Democratic candidate for the U.S. Senate, Elizabeth Warren addresses an audience during a campaign rally at a high school in Braintree, Mass., Sunday, Nov. 4, 2012. Both Warren and incumbent U.S. Sen. Scott Brown, R-Mass., continue their push around the state in the final days before Election Day. Warren was introduced by U.S. Sen. John Kerry, D-Mass., at the rally. (AP Photo/Steven Senne)
Democratic candidate for U.S. Senate Elizabeth Warren, left, reacts as she is introduced by Massachusetts State Rep. Niki Tsongas at a campaign rally in Lowell, Mass. Friday, Nov. 2, 2012. Warren is challenging Republican incumbent Sen. Scott Brown. (AP Photo/Elise Amendola)
Democrat Elizabeth Warren takes the stage after defeating incumbent GOP Sen. Scott Brown in the Massachusetts Senate race, during an election night rally at the Fairmont Copley Plaza hotel in Boston, Tuesday, Nov. 6, 2012. (AP Photo/Michael Dwyer)
Rep.-elect Katherine Clark, D-Mass., right, stands with Sen. Elizabeth Warren, D-Mass., after Clark posed for a photo during her ceremonial swearing-in ceremony on Capitol Hill in Washington, Thursday, Dec. 12, 2013. (AP Photo/Susan Walsh)
Democratic U.S. Sen. Elizabeth Warren, left, of Massachusetts and Kentucky democratic Senatorial candidate Alison Lundergan Grimes wave to supporters at at rally on Sunday, June 29, 2014 at the University of Louisville in Louisville, Ky. Warren has been canvassing the country following a failed vote in the U.S. Senate that would have allowed some people to refinance their student loan debt to take advantage of lower interest rates. (AP Photo/Timothy D. Easley)
Sen. Elizabeth Warren, D-Mass. speaks about raising wages during the forum AFL-CIO National Summit, Wednesday, Jan. 7, 2015, at Gallaudet University in Washington. (AP Photo/Jose Luis Magana)
WASHINGTON, DC - MAY 12: Sen. Elizabeth Warren (D-MA) speaks about the release of a new report authored by Nobel-prize winning economist Joseph Stiglitz published by the Roosevelt Institute May 12, 2015 in Washington, DC. The report, titled 'New Economic Agenda for Growth and Shared Prosperity', discusses the current distribution of wealth in the U.S. and offers proposals for modifying that distribution. (Photo by Win McNamee/Getty Images)
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And at Monday's fundraiser, one of the largest of her 2016 campaign, Clinton likely raked in hundreds of thousands of dollars from the 1,000 attendees, which included other members of Congress, wealthy donors, and prominent Washington Democrats.

But Warren's absence spoke to a question that has nipped at Clinton's heels throughout her campaign: Will her overwhelming support from the party's establishment be matched by enthusiasm among the party's grassroots base?

Warren was invited to participate in the fundraiser, but did not attend because she is not yet backing Clinton or any candidate in the 2016 Democratic primary.

"We're honored to have 13 women Senators coming together to endorse and support Hillary Clinton. This is a sign of the broad support Clinton is receiving from women across the country who know she'll fight for us," said Clinton campaign spokesperson Christina Reynolds.

See photos from Clinton's 2016 campaign:

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Hillary Clinton's 2016 campaign
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Clinton basks in glow of women senators -- with 1 absence
BALTIMORE, MD - APRIL 10: Democratic presidential candidate Hillary Clinton holds a campaign rally at City Garage April 10, 2016 in Baltimore, Maryland. Voters will head to polling places for Maryland's presidential primary April 26. (Photo by Chip Somodevilla/Getty Images)
Democratic U.S. presidential candidate Hillary Clinton laughs as she listens to Representative Steve Israel (D-NY) speak on a gun control panel in Port Washington, New York April 11, 2016. REUTERS/Lucas Jackson
NEW YORK, NY - APRIL 09: Democratic presidential candidate Hillary Clinton holds a Latino organizing event on April 9, 2016 while campaigning in the Brooklyn Borough of New York City. The New York Democratic primary is scheduled for April 19th. (Photo by Andrew Renneisen/Getty Images)
SPRINGFIELD, MA - FEBRUARY 29: Democratic presidential candidate former Secretary of State Hillary Clinton speaks during a 'Get Out The Vote' rally at the Lyman & Merrie Wood Museum of Springfield History on February 29, 2016 in Springfield, Massachusetts. Hillary Clinton is campaigning in Massachusetts and Virginia ahead of Super Tuesday. (Photo by Justin Sullivan/Getty Images)
BOSTON, MA - Former Secretary of State Hillary Clinton speaks to supporters at the Old South Meeting Hall during a rally in Boston, Massachusetts on Monday February 29, 2016. (Photo by Melina Mara/The Washington Post via Getty Images)
MINNEAPOLIS, MN - MARCH 01: Democratic presidential candidate former Secretary of State Hillary Clinton greets patrons at Mapps Coffee on March 1, 2016 in Minneapolis, Minnesota. Hillary Clinton is campaigning in Minnesota as Super Tuesday voting takes place in 12 states. (Photo by Justin Sullivan/Getty Images)
Democratic presidential candidate Hillary Clinton greets supporters as she arrives at a rally at Abraham Lincoln High School in Des Moines, Iowa, Sunday, Jan. 31, 2016. (AP Photo/Andrew Harnik)
Democratic presidential candidate Hillary Clinton speaks at a rally at Abraham Lincoln High School in Des Moines, Iowa, Sunday, Jan. 31, 2016. (AP Photo/Andrew Harnik)
Democratic presidential candidate Hillary Clinton, accompanied by her daughter Chelsea Clinton, reacts to applause as she arrives for a rally at Abraham Lincoln High School in Council Bluffs, Iowa, Sunday, Jan. 31, 2016. (AP Photo/Andrew Harnik)
Democratic presidential candidate Hillary Clinton, left, hugs Annette Bebout, 73, of Newton, during a campaign event at Berg Middle School, Thursday, Jan. 28, 2016 in Newton, Iowa. Bebout told her story of how she lost her home to the audience. (AP Photo/Paul Sancya)
Democratic presidential candidate Hillary Clinton, accompanied by former President Bill Clinton, right, and their daughter Chelsea Clinton, left, arrives to speak at a rally at Washington High School in Cedar Rapids, Iowa, Saturday, Jan. 30, 2016. (AP Photo/Andrew Harnik)
Democratic presidential candidate Hillary Clinton speaks at a rally at BR Miller Middle School in Marshalltown, Iowa, Tuesday, Jan. 26, 2016. (AP Photo/Andrew Harnik)
Democratic presidential candidate, Hillary Clinton makes a point during the Brown & Black Forum, Monday, Jan. 11, 2016, in Des Moines, Iowa. (AP Photo/Charlie Neibergall)
Democratic presidential candidate Hillary Clinton, right, and high school teacher David Swaney laugh about their colorful outfits before Swaney asks Clinton a question during a town hall at NewBo City Market in Cedar Rapids, Iowa, Monday, Jan. 4, 2016. (AP Photo/Patrick Semansky)
Democratic presidential candidate Hillary Clinton reacts to applause from the audience while standing with Brenda Bouchard, an Alzheimer's research advocate, during a town hall style campaign event, Tuesday, Dec. 29, 2015, at South Church in Portsmouth, N.H. (AP Photo/Steven Senne)
Democratic presidential candidate Hillary Clinton speaks about her counterterrorism strategy during a speech at the University of Minnesota Tuesday, Dec. 15, 2015, in Minneapolis. (AP Photo/Charlie Neibergall)
Democratic presidential candidate Hillary Clinton meets local residents at Apple Orchard Cafe Friday, Dec. 4, 2015, in Fort Dodge, Iowa. (AP Photo/Charlie Neibergall)
Hillary Rodham Clinton reacts as she talks to supporters after a Democratic presidential primary debate, Saturday, Nov. 14, 2015, in Des Moines, Iowa. (AP Photo/Charlie Neibergall)
Democratic presidential candidate Hillary Rodham Clinton greets supporters before speaking at a campaign rally in Boulder, Colo., Tuesday, Nov. 24, 2015. (AP Photo/Brennan Linsley
Democratic presidential candidate Hillary Rodham Clinton smiles as she arrives to speak at a town hall meeting Sunday, Nov. 22, 2015, in Clinton, Iowa. (AP Photo/Charlie Neibergall)
Democratic presidential candidate Hillary Rodham Clinton speaks from a gymnasium side porch to people who weren't able to fit in to hear her speech at Fisk University Friday, Nov. 20, 2015, in Nashville, Tenn. (AP Photo/Mark Humphrey)
Democratic presidential candidate Hillary Rodham Clinton shakes hand with a supporter during a town hall meeting Tuesday, Nov. 3, 2015, in Coralville, Iowa. (AP Photo/Charlie Neibergall)
Democratic presidential candidate Hillary Rodham Clinton speaks to customers at the White Mountain Cafe & Bookstore, Thursday, Oct. 29, 2015, in Gorham, N.H. (AP Photo/Robert F. Bukaty)
Democratic presidential candidate Hillary Rodham Clinton speaks during a meeting of the Alabama Democratic Conference in Hoover, Ala., Saturday, Oct. 17, 2015. Clinton tells black Alabama Democrats that she'd champion voting rights in the White House. She says Republicans are dismantling the progress of the civil rights movement. (AP Photo/Mark Almond)
MOUNT VERNON, IOWA - OCTOBER 7: Former Secretary of State Hillary Clinton speaks to voters during an outdoor town hall meeting at Cornell College in Mount Vernon, Iowa on Wednesday October 7, 2015. (Photo by Melina Mara/The Washington Post via Getty Images)
Democratic presidential candidate Hillary Rodham Clinton reacts to a supporter before speaking at a community forum, Tuesday, Oct. 6, 2015, in Davenport, Iowa. (AP Photo/Charlie Neibergall)
MUSCATINE, IOWA - OCTOBER 6: Former Secretary of State Hillary Clinton speaks to a voter before leaving a farm in Muscatine, Iowa on Tuesday October 6, 2015. (Photo by Melina Mara/The Washington Post via Getty Images)
MANCHESTER, NH - OCTOBER 05: Democratic presidential candidate Hillary Rodham Clinton holds a town hall meeting at the Manchester Community College on October 5, 2015 in Manchester, New Hampshire. Clinton spoke about the need for gun control on the wake of a mass shooting at another community college in Oregon. (Photo by Alfredo Sosa/The Christian Science Monitor via Getty Images)
Democratic presidential candidate Hillary Rodham Clinton gestures as she speaks at Human Rights Campaign gathering in Washington, Saturday, Oct. 3, 2015. ( AP Photo/Jose Luis Magana)
DAVIE, FL - OCTOBER 02: Democratic presidential candidate Hillary Clinton speaks about gun control during her campaign stop at the Broward College à Hugh Adams Central Campus on October 2, 2015 in Davie, Florida. Hillary Clinton continues to campaign for the nomination of the Democratic Party as their presidential candidate. (Photo by Joe Raedle/Getty Images)
Democratic presidential candidate Hillary Rodham Clinton speaks at a grassroots organizing meeting at Philander Smith College Monday, Sept. 21, 2015, in Little Rock, Ark. (AP Photo/Gareth Patterson)
WASHINGTON, DC - SEPTEMBER 19: Hillary Clinton attends the Phoenix Awards Dinner at the 45th Annual Legislative Black Caucus Foundation Conference at Walter E. Washington Convention Center on September 19, 2015 in Washington, DC. (Photo by Earl Gibson III/Getty Images)
MANCHESTER, NH - SEPTEMBER 19: Democratic presidential candidate Hillary Clinton claps on stage during the New Hampshire Democratic Party Convention at the Verizon Wireless Center on September 19, 2015 in Manchester, New Hampshire. Challenger for the democratic vote Sen. Bernie Sanders (I-VT) has been gaining ground on Clinton in Iowa and New Hampshire. (Photo by Scott Eisen/Getty Images)
PORTLAND, ME - SEPTEMBER 18: Hillary Clinton brings her Democratic presidential campaign to Maine for the first time, speaking at King Middle School. Clinton is welcomed as she is introduced at the event. (Photo by Derek Davis/Portland Press Herald via Getty Images)
CEDAR RAPIDS, IA - SEPTEMBER 7: Democratic Presidential hopeful Hillary Clinton takes time to meet supporters and take photos at the Annual Hawkeye Labor Council AFL-CIO Labor Day picnic on September 7, 2015 at Hawkeye Downs in Cedar Rapids, Iowa. Clinton spent a busy Labor Day weekend in Iowa, meeting supporters throughout the state while trying to maintain a lead over Bernie Sanders for the Democratic nomination. (Photo by David Greedy/Getty Images)
US Democratic presidential candidate Hillary Clinton takes part in a discussion after speaking about the Iran nuclear deal at the Brookings Institution in Washington, DC, on September 9, 2015. Clinton expressed firm support for the nuclear accord with Iran, calling it flawed but still strong. Clinton added that the agreement must be strictly enforced and said that if elected president next year, she would not hesitate to use military force if Iran fails to live up to its word and tries to develop a bomb. AFP PHOTO/NICHOLAS KAMM (Photo credit should read NICHOLAS KAMM/AFP/Getty Images)
PORTSMOUTH, NH - SEPTEMBER 5: Democratic presidential candidate Hillary Clinton and U.S. Senator Jeanne Shaheen take an off the schedule stop in the River Run Bookstore before shaking hands with onlookers on September 5, 2015 in Portsmouth, New Hampshire. (Photos by Charles Ommanney/The Washington Post via Getty Images)
PORTSMOUTH, NH - SEPTEMBER 5: Democratic Presidential candidate Hillary Clinton receives an endorsement from U.S. Senator Jeanne Shaheen (D-NH) September 5, 2015 in Portsmouth, New Hampshire. Clinton attended a Women for Hillary event at Portsmouth High School. (Photo by Darren McCollester/Getty Images)
PORTSMOUTH, NH - SEPTEMBER 5: Democratic Presidential candidate Hillary Clinton walks downtown Portsmouth and takes pictures with people September 5, 2015 in Portsmouth, New Hampshire. Clinton attended a Women for Hillary event at Portsmouth High School earlier in the day and received an endorsement from U.S. Senator Jeanne Shaheen (D-NH). (Photo by Darren McCollester/Getty Images)
LAS VEGAS, NEVADA - AUGUST 18: Former Secretary of State Hillary Clinton answers questions from journalists after speaking to north Las Vegas voters at a town hall meeting in Las Vegas, on Tuesday, August 18, 2015. The former Secretary was answering questions about emails sent and received a private server system, now in question, while she was the Secretary of State. (Photo by Melina Mara/The Washington Post via Getty Images)
UNITED STATES - August 15: Democratic presidential candidate Hillary Rodham Clinton greets fairgoers as she tours the Iowa State Fair in Des Moines, Iowa, on Saturday, August 15, 2015. (Photo By Al Drago/CQ Roll Call)
Democratic presidential candidate Hillary Rodham Clinton tours the Des Moines Area Rapid Transit Central Station with general manager Elizabeth Presutti, left, and building superintendent Keith Welch, Monday, July 27, 2015, in Des Moines, Iowa. (AP Photo/Charlie Neibergall)
CARROLL, IA - JULY 26: Democratic presidential hopeful and former Secretary of State Hillary Clinton speaks to guests gathered for a house party on July 26, 2015 in Carroll, Iowa. Although Clinton leads all other Democratic contenders, a recent poll had her trailing several of the Republican candidates in Iowa. (Photo by Scott Olson/Getty Images)
Democratic presidential hopeful Hillary Rodham Clinton greets supporters after a campaign event, Thursday, July 23, 2015 in Columbia, S.C. Clinton talked about what she said was a lack of educational and economic opportunities, and a criminal justice system that treats blacks more harshly than whites. (AP Photo/Stephen B. Morton)
Chelsea Galinos, 21, left, who painted a picture of the democratic presidential hopeful Hillary Rodham Clinton, right, greets Clinton after a campaign event in New York, Monday, July 13, 2015. (AP Photo/Seth Wenig)
Democratic presidential candidate Hillary Rodham Clinton speaks during a campaign stop at the Iowa City Public Library, Tuesday, July 7, 2015, in Iowa City, Iowa. (AP Photo/Charlie Neibergall)
FILE - In this June 20, 2015, file photo, Democratic presidential candidate Hillary Rodham Clinton speaks at the U.S. Conference of Mayors 83rd Annual Meeting in San Francisco. Clinton’s presidential campaign jumped on the Supreme Court decision, changing its red campaign logo to a rainbow colored H, releasing a gauzy video of gay wedding ceremonies, and blasting out supportive tweets aimed at building its campaign list. But like President Barack Obama, such expressions of support mark a remarkable shift for Clinton, who opposed gay marriage for more than two decades as a first lady, a U.S. senator and a presidential candidate. (AP Photo/Mathew Sumner, File)
Democratic presidential candidate Hillary Rodham Clinton speaks to supporters during a rally, Sunday, June 14, 2015, in Des Moines, Iowa. Seeking an army of volunteers, Clinton is trying to build an organizational edge in Iowa as some of her lesser-known Democratic rivals clamor for attention in the state that tripped up her first presidential campaign. (AP Photo/Charlie Neibergall)
Democratic presidential candidate Hillary Rodham Clinton speaks to supporters during a rally, Sunday, June 14, 2015, in Des Moines, Iowa. Clinton's campaign has signaled Iowa will be the centerpiece of its ground game. (AP Photo/Charlie Neibergall)
Democratic presidential candidate former Secretary of State Hillary Rodham Clinton waves to supporters as her husband former President Bill Clinton, second from right, Chelsea Clinton, second from left, and her husband Marc Mezvinsky, join on stage Saturday, June 13, 2015, on Roosevelt Island in New York. (AP Photo/Frank Franklin II)
Democratic presidential candidate, former Secretary of State Hillary Rodham Clinton speaks at the "Hillary For America" official campaign launch event at Four Freedoms Park, Roosevelt Island on Saturday, June 13, 2015, in New York. (Photo by Greg Allen/Invision/AP)
Supporters watch as democratic presidential candidate, former Secretary of State Hillary Rodham Clinton speaks Saturday, June 13, 2015, on Roosevelt Island in New York. (AP Photo/Frank Franklin II)
Democratic presidential candidate, former Secretary of State Hillary Rodham Clinton speaks to supporters Saturday, June 13, 2015, on Roosevelt Island in New York. (AP Photo/Frank Franklin II)
Democratic presidential candidate Hillary Rodham Clinton delivers a speech at Texas Southern University in Houston, Thursday, June 4, 2015. Clinton is calling for an expansion of early voting and pushing back against Republican-led efforts to restrict voting access, laying down a marker on voting rights at the start of her presidential campaign. (AP Photo/Pat Sullivan)
CHICAGO, IL - MAY 20: Democratic presidential hopeful and former Secretary of State Hillary Clinton arrives for a meeting with parents and child care workers at the Center for New Horizons on May 20, 2015 in Chicago, Illinois. Clinton arrived in Chicago after campaigning Monday and Tuesday in Iowa. (Photo by Scott Olson/Getty Images)
Democratic presidential candidate Hillary Rodham Clinton greets a local resident while visiting local shops on main street in Independence, Iowa, Tuesday, May 19, 2015. (AP Photo/Charlie Neibergall)
LAS VEGAS, NV - MAY 05: Democratic presidential candidate and former U.S. Secretary of State Hillary Clinton (C) poses with students and faculty after speaking at Rancho High School on May 5, 2015 in Las Vegas, Nevada. Clinton said that any immigration reform would need to include a path to 'full and equal citizenship.' (Photo by Ethan Miller/Getty Images)
Hillary Rodham Clinton, a 2016 Democratic presidential contender, steps to the podium to speak at the David N. Dinkins Leadership and Public Policy Forum, Wednesday, April 29, 2015, in New York. (AP Photo/Mark Lennihan)
NEW YORK, NY - APRIL 23: Hillary Rodham Clinton (L) and actress Maggie Gyllenhaal attend the 2015 DVF Awards at United Nations on April 23, 2015 in New York City. (Photo by Michael Stewart/FilmMagic)
NEW YORK, NY - APRIL 29: Democratic presidential hopeful and former Secretary of State Hillary Clinton speaks during the David N. Dinkins Leadership and Public Policy Forum at Columbia University April 29, 2015 in New York City. Clinton addressed the unrest in Baltimore, called for police body cameras and a reform to sentencing. (Photo by Kevin Hagen/Getty Images)
Democratic presidential candidate Hillary Rodham Clinton meets with employees at Whitney Brothers during a campaign stop, Monday, April 20, 2015, in Keene, N.H. (AP Photo/Jim Cole)

Hillary Clinton announced her campaign for president on Sunday April, 12, 2015 with a video on YouTube. 

(Screenshot from YouTube)

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Sanders has captured the voting bloc that would have been Warren's had she decided to run, but he has so far struggled to expand his support beyond that -- especially among his party's leadership. He is the lone member of the Senate supporting his presidential campaign, and he has just two members of the House in his corner.

Sanders has attempted to play this to his advantage. "Now is not the time for establishment politics, now is the time for a political revolution," he said at the New Hampshire Democratic Party's Jefferson Jackson dinner Sunday night in Manchester.

An endorsement from Warren, who is one of just six Democrats in the upper chamber who has yet to back Clinton, would be a powerful validator for either candidate.

Check out more coverage of Hillary Clinton:

As New Clinton Emails Are Released, Where Does Hillary Stand?



Earlier this year, while weighing a potential White House bid, Vice President Joe Biden met with Warren for what she called "a good, long, rambly conversation" at the Naval Observatory.

Clinton's backers are convinced she'll come on board eventually. "Elizabeth. I think in her course of time, she's going to come out for Hillary," California Sen. Barbara Boxer told MSNBC's Steve Kornacki Monday afternoon.

Aides to both Clinton and Warren seemed to chafe at the latest round of questioning from reporters about the relationship between the two women, which has existed in some form since Warren visited then-first lady Clinton to lobby her on a bankruptcy bill in the 1990s, but has never been particularly close.

Warren has been publicly pushing presidential candidates to support a bill that would put restrictions on the so-called "revolving door" between Wall Street and government, and is a force in the Senate for stricter rules on the financial industry and consumer protection.

In 2013, all 14 Democratic women senators -- including Warren -- signed on to a letter organized by California Sen. Barbara Boxer urging Clinton to run for president. Warren has said calling on Clinton to run is not the same thing as an endorsement.

The senator is still not ready to make an endorsement, Warren allies say, though she has indicated she will do so before the Democratic contest is over. "I imagine that's what I'll do," she told The Boston Globe when asked if she would endorse during the primary.

Despite the conspicuous absence of Warren, rarely has Clinton's lock on the establishment support been so clear as it was Monday night. Speaking to room packed by Washington notables, 13 of Sanders' colleagues spoke back-to-back about why they were choosing their former colleague over their current one, though none of them mentioned him by name.

"We have one great candidate," said California Sen. Dianne Feinstein. "You come to the conclusion that this is really the only candidate out there that has an opportunity because of the knowledge that's in her brain to solve some of the problems that we face as the most indispensable nation on earth."

New Hampshire Sen. Jeanne Shaheen, who previously served as governor and whose political apparatus has been put to work for Clinton, vowed that the former secretary of state would win her state's critical first-in-the-nation primary. "Hillary's going to win New Hampshire," she said.

Following Shaheen, Sen. Amy Klobuchar joked she can see Iowa from her porch in neighboring Minnesota. "And I can tell you this. Hillary Clinton is going to win Iowa!" she said.

"She is the woman for this job," added Washington Sen. Patty Murray. "Just like all of us, she still puts her pantsuits on one leg at a time."

The majority of the senators cited Clinton's foreign policy experience as a reason for backing her, often highlighting her tenure as secretary of state. The women also drew sharp contrasts between Clinton and Republican presidential candidates. And all of the senators said it was time for the country to elect a woman president, and the campaign unveiled a new video titled "44 Boys Is Too Many," which featured girls saying the same.

Clinton was clearly thrilled to be on stage with her former colleagues, and singled out Sen. Barbara Mikulski, who is retiring this year, noting Mikulski is the reason Clinton was allowed to wear pants on the Senate floor. "You know what we saw in Colorado Springs the other night was just horrific and we have to stand up for the rights of women to get the healthcare that they need and we have strong," she said. She went on to praise the "strong soldiers and fighters in pursuit of that behind me."

Clinton touched on the theme earlier in the day during an appearance at the Atlantic Council in Washington in which she discussed foreign policy. "It would be probably predictable for me to say this but there's a lot we can learn from Latin America's success at electing women," she said.

Photos from Clinton's appearance at the Atlantic Council:

8 PHOTOS
Hillary Clinton at Atlantic Council Women's Leadership in Latin America Initiative, Nov. 30
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Clinton basks in glow of women senators -- with 1 absence
Democratic presidential candidate Hillary Clinton speaks at the Atlantic Council Women's Leadership in Latin America Initiative in Washington, Monday, Nov. 30, 2015. (AP Photo/Pablo Martinez Monsivais)
Democratic presidential candidate Hillary Clinton, followed by Adrienne Arsht Latin American Center Director Peter Schechter, arrives before speaking at the Atlantic Council Women's Leadership in Latin America Initiative in Washington, Monday, Nov. 30, 2015. (AP Photo/Pablo Martinez Monsivais)
Democratic presidential candidate Hillary Clinton smiles as she walks off-stage after speaking at the Atlantic Council Womenâs Leadership in Latin America Initiative in Washington, Monday, Nov. 30, 2015. (AP Photo/Pablo Martinez Monsivais)
A member of the audience uses a tablet to record Democratic presidential candidate Hillary Clinton's remarks at the Atlantic Council Womenâs Leadership in Latin America Initiative in Washington, Monday, Nov. 30, 2015. (AP Photo/Pablo Martinez Monsivais)
Democratic presidential candidate Hillary Clinton speaks at the Atlantic Council Women's Leadership in Latin America Initiative in Washington, Monday, Nov. 30, 2015. (AP Photo/Pablo Martinez Monsivais)
Assistant Secretary of State for Latin America Roberta Jacobson, reacts as she meets with guest while waiting for the arrival of Democratic presidential candidate Hillary Clinton to speak at the Atlantic Council Women's Leadership in Latin America Initiative in Washington, Monday, Nov. 30, 2015. Jacobson was the chief U.S. negotiator at the talks to resume diplomatic relations with Cuba, as recently nominates as the new U.S. ambassador to Mexico. (AP Photo/Pablo Martinez Monsivais)
Democratic presidential candidate Hillary Clinton smiles while speaking at the Atlantic Council Womenâs Leadership in Latin America Initiative in Washington, Monday, Nov. 30, 2015. At left is Mexican Sen. Ninfa Salinas who was also on the panel discussion at center. (AP Photo/Pablo Martinez Monsivais)
Democratic presidential candidate Hillary Clinton greets guests before speaking at the Atlantic Council Women's Leadership in Latin America Initiative in Washington, Monday, Nov. 30, 2015. (AP Photo/Pablo Martinez Monsivais)
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