US Senate Republicans blocked a bill titled the Domestic Terrorism Prevention Act in Congress on Thursday that Democrats viewed as a response to a white supremacist's killing of 10 black people this month and a potential gateway to a gun control bill.
Two days after another mass killing of 19 young children and two teachers at a Texas school, senators voted 47-47 along party lines, short of the 60 senators required to launch debate, to reject the bill authorising federal agencies to monitor and report jointly on domestic terrorism within the US, including incidents related to white supremacy.
Republicans said the legislation was unnecessary as Democratic President Joe Biden already had the authority to organise his administration's response to violent extremism.
Democrats insisted the bill was needed to bolster the federal government's response to rising incidents of domestic violent extremism.
The outcome, which had been expected, cut off the chance for any immediate action on gun-control legislation to address a rising tide of mass shootings in the US. Senators were due to leave Washington for a one-week Memorial Day holiday.
Mass shootings in recent years have provoked flurries of discussion in Congress on what to do about gun violence but little action as the two parties are deeply divided on gun rights. Americans have little confidence in Congress' ability to solve the problem, with a Reuters/Ipsos poll on Tuesday showing that only 35 per cent believe politicians will act.
The House of Representatives passed the domestic terrorism bill along party lines last week, after an avowed white supremacist killed the 10 black people in a livestreamed shooting at a supermarket in Buffalo, New York, on May 14.
Democrats and some Republicans in the Senate have discussed the possibility of bipartisan legislation to address the issue, including proposals to expand background checks for gun purchasers and to keep firearms out of the hands of the mentally ill.
A total of 79 per cent of Americans — and 78 per cent of Republicans — are more likely to vote for a candidate in November's midterm elections who supports passing red flag laws of that kind, the Reuters/Ipsos poll found.
Senate Majority Leader Chuck Schumer said at least five Democratic politicians including Senator Chris Murphy have reached out to Republicans about possible measures related to gun and school safety.
Mr Murphy, who advocates gun restrictions, said talks with Republicans would continue into next week. But the odds are slim at best that the Senate will enact any bill to restrict guns.
"None of us are under any illusions that this will be easy," Mr Schumer said on the Senate floor, accusing Republicans of being in the "vice grip" of the US gun lobby. But he said: "We need to give it a short amount of time to try."
With the 100-seat Senate split 50-50, gun legislation would need 10 Republican votes to meet the chamber's 60-vote threshold for passing most bills.
Republicans generally oppose gun restrictions and instead assert a right to bear arms protected by the Second Amendment of the US Constitution.
Mr Schumer has taken initial steps towards a possible vote on other legislation to tighten background checks for gun buyers if current bipartisan talks prove fruitless.