Democrats angered over the lack of action on gun control after this weekend's shooting in Orlando launched a 15-hour filibuster on the Senate floor Wednesday, vowing to continue talking until some progress is made on a bill to bar sales of guns to people suspected of being terrorists.
Sen. Chris Murphy of Connecticut began the effort before noon and said he would remain on the floor "until we get some signal, some sign that we can come together."
He yielded the floor at 2:11 a.m., saying he had won commitments from Republican leaders that they would hold votes on amendments to expand background checks and ban gun sales to suspected terrorists. It is unlikely that those amendments will pass.
Murphy, an outspoken proponent of gun control, represents Newtown, where the 2012 elementary school shooting occurred.
"I know this is uncomfortable," Murphy said Wednesday evening, six hours into his talk. "Those of us who are on the floor today...said 'enough, enough.' We've got to show a signal to the American public that we care so deeply about the consequences of inaction that we're going to stop this process until we can't stand any longer."
Maryland's senators -- both Democrats -- also spoke on the floor in an effort to give Murphy some relief.
"I noticed that in the Orlando tragedy, one of the weapons that was used was an assault weapon, a military style weapon," said Sen. Ben Cardin. "I must tell you that in my observations in Maryland, I don't know too many people who need to have that type of weapon in order to do hunting in my state or to keep themselves safe."
In the days following the Orlando shooting, Democrats have pressed for a measure that would ban people on government terror watch lists from obtaining weapons. Lawmakers want to attach an amendment on that issue to a criminal justice spending bill that pending in the Senate.
Republicans have supported another bill that would let the government delay firearms sales to suspected terrorists for up to 72 hours. Prosecutors would have to persuade a judge to block the transaction permanently during that time.
Sen. John Cornyn, a Texas Republican, said he is talking with Democrats in search of a compromise.
"We're trying, we're trying," Cornyn said. "But we're not going to presume somebody's guilty and deny them due process of law, we're going to require the government to show some evidence and to provide for a constitutional process, that's where we differ."
Cornyn described the filibuster as "just filling dead air" while those negotiations continue.
"Anyone on a terror watchlist who tries to buy a gun should be thoroughly investigated by the FBI and the sale delayed while the investigation is ongoing," the National Rifle Association's Institute for Legislative Action said in a statement. "If an investigation uncovers evidence of terrorist activity or involvement, the government should be allowed to immediately go to court, block the sale, and arrest the terrorist."
The Orlando shooter, Omar Mateen, was added to a government watch list of individuals known or suspected of being involved in terrorist activities in 2013, when he was investigated for inflammatory statements to co-workers. But he was pulled from that database when that investigation was closed 10 months later. And so it is not likely the legislation being debated would have stopped the shooting had it been in place.
Sen. Barbara A. Mikulski, the top Democrat on the Senate Appropriations Committee, offered an amendment Wednesday shortly before the filibuster began to provide an additional $190 million in funding to the Federal Bureau of Investigation. Most of that money would be used for the agency's counter-terrorism efforts. About $15 million would be directed to training to help stop active shooter situations.
"It was a terrible act of terrorism and hate, the killing of 49 innocent people -- with a death toll possibly on the rise -- at a nightclub in Orlando," Mikulski said on the floor. "It wasn't the first time a terrorist with hate in his heart and a gun in his hand had mowed down his fellow citizens with a high-powered weapon."
The Associated Press contributed to this article.