NEW YORK/WASHINGTON, June 8 (Reuters) - U.S. Senator Elizabeth Warren will soon endorse presumptive Democratic presidential nominee Hillary Clinton and, while not currently interested in serving as her running mate, has not ruled it out, several sources close to Warren told Reuters.
Advisers to Warren, a fiery critic of Wall Street and a popular figure among progressive Democrats, have been in close contact with Clinton's campaign team and the conversations have increased in frequency in recent weeks, the sources said.
Warren, 66, represents her home state of Massachusetts in the U.S. Senate. The sources said that foremost in her thinking is how best to help the Democratic Party defeat the presumptive Republican nominee Donald Trump in the Nov. 8 presidential election and advance issues such as income inequality which top Warren's agenda.
An endorsement of Clinton could come within a week or two, one of the sources said. Clinton has been appealing for Democratic Party unity. On Twitter over the weekend, Warren echoed that call and emphasized the importance of the party coming together to beat Trump.
"Get ready, Donald," she tweeted. "We're coming."
See Elizabeth Warren through the years:
US Senator Warren to endorse Clinton, sources say
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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Warren has stayed neutral in the Democratic primary race, notably remaining the only woman senator not throwing her support behind the first woman presidential nominee of a major political party.
Were she to join the Clinton ticket, she could help energize progressives and win over supporters of Clinton's rival Bernie Sanders, a democratic socialist U.S. senator from Vermont. Sanders' calls for reining in Wall Street and breaking up big banks dovetail with Warren's views.
Warren, a former special adviser in the Obama administration for the Consumer Financial Protection Bureau, has been one of the Democrats' most effective Trump critics.
An ongoing feud with Trump gained steam on social media with a series of posts in which she labeled the celebrity businessman racist, sexist and xenophobic and said she was going to fight to make sure his "toxic stew of hatred and insecurity never reaches the White House."
Warren joined Clinton late last month in criticizing Trump for rooting for the 2008 financial crisis and delivered a 10-minute invective on the subject at an annual Washington gala two weeks ago.
"What kind of a man roots for people to get thrown out of their house? I'll tell you exactly what kind of man does that," Warren said. "It is a man who cares about no one but himself - a small insecure money-grubber who doesn't care who gets hurt so long as he makes a profit off it."
Trump has ridiculed Warren by calling her Pocahontas in a mocking reference to her having said in the past that she had Native American ancestry. Pocahontas was a famous Native American in early colonial Virginia.
(Additional reporting by Megan Cassella and Amanda Becker in Washington; Editing by Amran Abocar and Howard Goller)
See some of Clinton's potential running mates:
Hillary Clinton potential running mates, VPs
US Senator Warren to endorse Clinton, sources say
The junior Democratic Senator from the swing state of Virginia could be a strategic selection for Hillary. Kaine also served as the governor of Virginia from 2006- 2010.
(Photo by Samuel Corum/Anadolu Agency/Getty Images)
The current U.S. Senator from Massachusetts is popular among progressive Democrats, and some even tried to draft her to run for president herself in 2016.
(Photo by Andrew Harrer/Bloomberg via Getty Images)
Insiders believe that the senior U.S. Senator from Ohio could help Clinton increase her popularity with working-class voters, a group she has yet to win in a big way so far in primary contests.
(Photo By Bill Clark/CQ Roll Call)
The U.S. Senator from New Jersey is both youthful and charismatic and would add racial diversity to a Clinton ticket.
(Photo by KK Ottesen for The Washington Post via Getty Images)
The current U.S. Secretary of Labor is considered a sleeper pick by many Democrats because he is not well known outside of D.C., but some believe his strength and popularity among union workers and other progressive groups could be an asset to Clinton's ticket.
(Photo By Tom Williams/CQ Roll Call)
The former mayor of San Antonio and current U.S. Secretary of Housing and Urban Development has been rumored as a possible running mate for Clinton for months, but in May he said in an interview that the Clinton campaign hasn't talked to him about the role.
(AP Photo/Eric Gay)
Insiders confirmed that Clinton is definitely considering a woman as her vice presidential pick, and as U.S. Senator from Minnesota, Klobuchar has a seat Democrats would likely maintain. She's also been described as "by far" the most popular politician in her state.
(AP Photo/Ann Heisenfelt)
The Independent from Vermont has become Hillary Clinton's primary rival for the Democratic nomination, garnering a surprising amount of support. Bringing Sanders onto the ticket could help to unite both sets of supporters who have been split in Democratic primaries.
(Photo by Ralph Freso/Getty Images)
A former 2016 rival of Hillary Clinton, and former Maryland governor, Martin O’Malley could help bring some executive experience, along with a slight youthful boost to the ticket.
(Photo by Joe Raedle/Getty Images)
The Secretary of Agriculture since 2009, Tom Vilsack also served as the governor of Iowa from 1999 to 2007. Vilsack could bring some governing experience along with swing state influence.
(BELGIUM - Tags: AGRICULTURE POLITICS BUSINESS)
Colorado Gov. John Hickenlooper delivers his annual State of the State address to lawmakers and guests, inside the state legislature, in Denver, Thursday, Jan. 14, 2016. Hickenlooper called upon Republicans and Democrats to return to an era of civility and compromise in his address to the Republican-controlled Senate and the Democrat-led House. (AP Photo/Brennan Linsley)
Evan Bayh could bring a more right leaning brand of politics to the ticket. Bayh previously served as the junior U.S. Senator from Indiana from 1999 to 2011, and also as the 46th Governor of Indiana from 1989 to 1997.
While the likelihood of him agreeing to take on the veep job again might be low, Biden's popularity among Democrats would likely boost Clinton's chances.
(Photo credit MANDEL NGAN/AFP/Getty Images)
Hillary's husband is technically allowed to serve in the job, and some legal experts even think he'd be able to take office if necessary. Unfortunately for the diehard Clinton supporters, a Clinton-Clinton ticket will probably be a dream that never comes true.