[WASHINGTON] Democrats claimed victory Thursday after persuading the US Senate to hold a vote next week on legislation that would bar terror suspects from buying firearms.
The debate - with the potential to turn vicious in a contentious presidential election year - comes with Republican White House hopeful Donald Trump signaling he could back moves to prevent people on terror watch lists or no-fly lists from buying guns.
The possible breakthrough in the Republican-controlled Senate could end a years-long logjam on how to reduce US gun violence, following last weekend's massacre of 49 people at a gay nightclub in Orlando, Florida - the deadliest mass shooting in US history.
Senate Democrats brought their pressure to bear by mounting a 15-hour marathon focused on reducing gun violence.
With support from a small number of Republicans, Democrats have questioned how a man investigated for suspected extremist ties and who previously figured on an FBI watch list was able to commit mass murder with a legally purchased assault rifle.
They got a strong boost from President Barack Obama who met Thursday with relatives of the Orlando victims, and urged lawmakers to "rise to the moment and do the right thing."
It will be a tall order: Republicans largely oppose legislation that would limit gun rights in any way.
"We don't take away citizens' rights without due process," House Speaker Paul Ryan told reporters Thursday.
"And so if you have a quick idea in the heat of the moment that says let's take away a person's rights without their due process, we're going to stand up and defend the Constitution."
The Democratic filibuster, which started Wednesday and ended early Thursday, was led by Senator Chris Murphy of Connecticut.
"I'm going to remain on this floor until we get some signal, some sign that we can come together." Mr Murphy and other went well past midnight discussing ways to reduce gun violence - a tactic that eventually prompted leaders to schedule a vote on gun measures.
Senate Majority Leader Mitch McConnell's office said votes on Democratic and Republican amendments will begin Monday, including on Democratic Senator Dianne Feinstein's "no-fly, no buy" amendment, under which people on US terror watch lists or no-fly lists would be barred from acquiring firearms.
Similar legislation failed last December, with all but one Senate Republican voting no.
Also getting a vote are measures that would extend background checks to sales at gun shows and on the Internet.
Despite the broad support such measures enjoy from most Americans, they remain controversial in Congress, and passage is seen as being unlikely in the toxic 2016 election climate.
Meanwhile Mr Trump, the presumptive Republican presidential nominee, made waves Wednesday when he tweeted that he would meet with the National Rifle Association "about not allowing people on the terrorist watch list, or the no fly list, to buy guns."
The shift may put Trump on a collision course with the powerful NRA, which has said that restrictions "like bans on gun purchases by people on 'watch lists' are ineffective, unconstitutional or both."
But on Wednesday it said it would meet with Mr Trump, and suggested in a statement it would be open to changes in the law to prevent certain gun purchases.
Mr Trump's Democratic presidential rival Hillary Clinton said she supports the limits pushed by Mr Murphy.
"Surely we can agree, if the FBI is watching you for suspected terrorist links, you should not be able to buy a gun with no questions asked," Mrs Clinton said.
The renewed push comes after a US government report showed that known terror suspects have passed background checks for gun sales 91 per cent of the time since 2004.
"I do think our filibuster made a difference," Mr Murphy told CBS television.
"Let's be honest. The Senate was not going to debate these measures, had no plans to talk about ending gun violence this week on the floor of the Senate," Mr Murphy said.
Among the Republicans who appear to be giving the measure support is Congressman Bob Dold, who is facing a tough re-election fight in Illinois.
"Thoughts and prayers are not enough," Mr Dold said this week on the House floor. "It's time for action."