WASHINGTON, Dec 3 (Reuters) - One day after a mass shooting in California that killed 14 people and wounded 21, Republicans and Democrats in the U.S. Senate jousted on Thursday over gun control but again failed to advance legislation addressing the violence.
Democrats tried to expand background checks to those purchasing weapons at gun shows and through intrastate Internet transactions. They also proposed closing a loophole allowing people on "terror watch lists" to buy guns and explosives.
Both efforts failed in the face of heavy Republican opposition.
Republicans said the government could mistakenly place innocent people on watch lists, denying them their constitutional rights to purchase guns. The influential National Rifle Association has also advanced that argument.
Texas Republican Senator John Cornyn failed to win an alternative putting gun sales on hold for 72 hours for people on watch lists. Critics have said such background checks could take longer to complete.
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UNITED STATES - SEPTEMBER 10: Yvonne Crasso, holds a picture of her sister Nina Michele Bradley, who was killed by a gun at age 23 in 2012, during a rally on the East Front lawn of the Capitol to demand that Congress take action on gun control legislation, September 10, 2015. Ashley Cech, whose mother Yvonne Cech, a librarian, survived the Sandy Hook shootings, appears with Crasso. The event, titled #Whateverittakes Day of Action, was hosted by Everytown for Gun Safety and featured speeches by political leaders and families of gun violence victims. (Photo By Tom Williams/CQ Roll Call)
WASHINGTON, USA - JANUARY 4: A group of people demonstrate in front of the White House for greater gun control to help curb gun violence in Washington, USA on January 4, 2015. (Photo by Samuel Corum/Anadolu Agency/Getty Images)
WASHINGTON, DC - DECEMBER 10: Natasha Christopher, center, holds up a photo of her son Akeal Christopher, who was 14 years old when he was shot in the back of the head and killed while walking home in Brooklyn, New York, during a press conference, on Capitol Hill on December 10, 2015 in Washington, D.C. The conference featured supporters of gun control and family members of gun violence victims. (Photo by Allison Shelley/Getty Images)
WASHINGTON, DC - DECEMBER 10: Miyoshia Bailey cries as she describes how her only son, Cortez Bailey, 23, was shot to death in Chicago, Illinois, during a press conference, on Capitol Hill on December 10, 2015 in Washington, D.C. The conference featured supporters of gun control and family members of gun violence victims. (Photo by Allison Shelley/Getty Images)
Amy Schumer reacts as her distant cousin, Senator Chuck Schumer, watches during a news conference in New York, Monday, Aug. 3, 2015. The Schumers are teaming up to try and enact gun control regulations. (AP Photo/Seth Wenig)
Amanda Wilcox, a member of the Brady Campaign to Prevent Gun Violence, shows a photo of her daughter, Laura, who was killed in a shooting at a mental health clinic in 2001, following a hearing on gun violence held in Sacramento, Calif., Monday, Dec. 14, 2015. Wilcox joined a panel that included law enforcement officials, an Arizona gun show dealer, a California gun club owner and other gun control advocates put together by Rep. Mike Thompson, D-St. Helena, chairman of the House Democrats' Gun Violence Prevention Task Force. (AP Photo/Rich Pedroncelli)
A volunteer sits by a campaign sign stating support of gun control before an event by Democratic presidential candidate Hillary Rodham Clinton, Friday, Oct. 2, 2015, at Broward College in Davie, Fla. (AP Photo/Lynne Sladky)
WASHINGTON, DC - FEBRUARY 05: Rep. Elizabeth Esty (D-CT) (L) and Sen. Richard Blumenthal (D-CT) are joined by Newtown Action Alliance Vice Chairman David Stowe (R) to announce the re-introduction of legislation that would ban high-capacity ammunition magazines at the U.S. Capitol February 5, 2015 in Washington, DC. Citing the 2012 mass shooting of children and teachers at Sandy Hook Elementary in Newtown, CT, Democratic members of the House and Senate joined the Connecticut delegation to support and emphasize the need for the proposed law. (Photo by Chip Somodevilla/Getty Images)
Andy Parker, father of WDBJ-TV reporter Alison Parker, speaks at a rally against gun violence, Thursday, Sept. 10, 2015, on Capitol Hill in Washington. (AP Photo/Susan Walsh)
Demonstrators march over the Brooklyn bridge during the third annual Brooklyn bridge march and rally to end gun violence Saturday, May 9, 2015, in New York. Organizers said the proliferation of guns results in an average of more than 80 deaths a day across the country. (AP Photo/Mary Altaffer)
FILE - In this April 18, 2013 file photo, community gun safety advocates and members of the public hold signs during a rally and vigil to honor victims of gun violence, sponsored by Colorado Ceasefire, on the steps of the Colorado State Capitol, in Denver. When a gunman opened fire inside a packed movie theater in July of 2012, killing 12, it helped revive the national debate over gun control. But, as the trial of theater shooter James Holmes is scheduled to begin Monday, April 27, 2015, Coloradoâs gun debate has quieted down. âItâs in a sort of gridlock,â said nonpartisan Denver pollster Floyd Ciruli. (AP Photo/Brennan Linsley, file)
People calling for gun control demonstrate on a street a few blocks away from the site of the National Rifle Association convention Saturday, April 11, 2015, in Nashville, Tenn. (AP Photo/Mark Humphrey)
Former Arizona Congresswoman Gabby Giffords, left, listens from the audience before speaking in support of Initiative 594, a measure seeking universal background checks on gun sales and transfers, Wednesday, Oct. 22, 2014, in Seattle. Giffords, who was wounded three years ago in Tucson, spoke as part of a cross-country tour to promote gun control. She appeared at a panel discussion on reducing gun violence against women and organizers said the focus is on background checks for gun buyers. Gifford's nine-state tour started more than a week ago in Maine where she advocated tougher laws to protect women from stalkers and domestic violence. (AP Photo/Elaine Thompson)
Actress Amanda Peet, left, holds her daughter alongside fellow actor Adam Scott, center, and relatives of gun violence victims at a rally outside city hall to call for tougher gun control laws, Saturday, June 14, 2014, in New York. The protest was underwritten by former New York Mayor Michael Bloomberg, one of the most visible gun control advocates in the U.S., and included relatives of some of those slain in the 2012 shooting rampage at Sandy Hook Elementary School. (AP Photo/John Minchillo)
Hundreds of demonstrators march across the Brooklyn Bridge to call for tougher gun control laws, Saturday, June 14, 2014, in New York. The protest was underwritten by former New York Mayor Michael Bloomberg, one of the most visible gun control advocates in the U.S., and included relatives of some of those slain in the 2012 shooting rampage at Sandy Hook Elementary School in Newtown, Conn. (AP Photo/John Minchillo)
Supporters of a new gun rights bill hold signs prior to a hearing on gun rights laws at the Statehouse in Boston, Tuesday, June 3, 2014. Supporters and opponents of tighter gun control measures gathered at the Statehouse for a public hearing on a wide-ranging gun bill. (AP Photo/Charles Krupa)
MaryAnn McHugh, of Nashua, left, talks with state Rep. Hank Parkhurst, D-Winchester, as she lobbies for gun control at the entrance of Represetatives Hall at the Statehouse Wednesday, Feb. 12, 2014, in Concord, N.H. The House is considering legislation to expand New Hampshire's background checks for gun sales and transfers to include gun shows. (AP Photo/Jim Cole)
In this Monday, Nov. 18, 2013 photo, gun-control advocates rally against gun violence in front of the state Capitol, in Denver. Gun-control supporters who gathered at the Colorado Capitol on Monday, Nov. 18, 2013 asked the Democratic state Legislature Monday not to revisit last session's gun-control package, which included expanded background checks and a limit on ammunition magazines. (AP Photo/Brennan Linsley)
Petitions for Initiative 594 are counted at the Secretary of State's office Wednesday, Oct. 9, 2013, in Olympia, Wash. Advocates seeking to expand the use of background checks on gun sales in Washington state turned in more than 250,000 signatures for the initiative, the first batch of petitions they plan to submit before a January deadline to qualify it to the Legislature. The plan would require background checks for online sales and private transactions of guns. (AP Photo/Elaine Thompson)
Carl Brooks of West Orange, N.J., who lost his nephew and brother-in-law in gun violence attends a rally on gun control Capitol Hill, in Washington, Thursday, Sept. 19, 2013. (AP Photo/Manuel Balce Ceneta)
Philadelphia Mayor Michael Nutter speaks during a demonstration Wednesday, Aug. 21, 2013, at Rittenhouse Square in Philadelphia. The event was held in support of legislation HR 1565 to expand background checks for gun sales. (AP Photo/Matt Rourke)
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The FBI is trying to determine whether a couple suspected of the shootings at a workplace in Southern California on Wednesday had links to Islamic militant groups.
In a news conference before the votes, Democratic Senator Richard Blumenthal said: "Congressis complicit in these mass murders when it fails to act."
Blumenthal's home state of Connecticut was the scene of a mass shooting three years ago when a 20-year-old gunman entered an elementary school and killed 20 children and six employees.
After that tragedy, gun control legislation appeared to gain traction, only to fail in 2013 following an emotional Senate debate.
With the latest mass shootings in Paris, as well as in Colorado and California fresh in the public's mind, Democrats argued sentiment was again turning in their favor on gun control.
"I think we are ... reaching a tipping point," New York Senator Charles Schumer said, adding that mass shootings "week after week" were "arousing the American conscience."
But given Thursday's Senate votes and recent public opinion polls, it is not apparent the United States has reached a "tipping point" in favor of stricter gun laws.
A Washington Post/ABC News poll last month found 82 percent thought gun violence was a very serious or somewhat serious problem. But opinion split almost evenly over whether enacting new laws to reduce gun violence or protecting the right to own guns was more important.
The poll also found that 63 percent blamed mass shootings on mental health problems, while 23 percent cited inadequate gun control.
(Reporting by Richard Cowan; Editing by Peter Cooney)