By Richard Cowan and Julia Edwards
Some Republican senators have tried to craft a compromise bill to impose limited gun restrictions in the face of pressure from Democrats and public rage over the Orlando mass shooting, the deadliest in modern US history.
A gunman killed 49 people at the Orlando, Florida, gay nightclub last Sunday (local time), sparking a scramble over competing gun measures in the US Senate.
While gun-control measures have failed to clear Congress in the past, the massacre, coupled with public pressure and a suggestion by Republican presidential candidate Donald Trump that he can work with gun rights lobbyists to bring about change, may be changing the picture.
Republicans over the years have blocked gun control measures saying they step on Americans' right to bear arms as guaranteed under the US Constitution. During a week-long Senate debate, Democrats generally have criticised proposed Republican measures as being ineffective.
Republicans and Democrats have offered four separate proposals to expand background checks on gun buyers and curb gun sales for people on terrorism "watch lists."
But they seem destined to fail because of partisan politics and a requirement that any proposal muster 60 of the 100 votes in the US Senate.
Republican Susan Collins of Maine, leading the new effort, is considering whether to allow guns to be purchased by people named on a broad terrorism watch list kept by the FBI, but not by people whose names appear on some more narrow lists, including a "no-fly" list that bans people from boarding planes.
The gun control issue is deeply divisive and there have been no major restrictions passed since 1994, when Congress imposed a ban on semi-automatic assault weapons. That expired after 10 years.
About 71 per cent of Americans, including eight out of 10 Democrats and nearly six out of 10 Republicans, favour at least moderate regulations and restrictions on guns, according to a Reuters/Ipsos poll conducted from Monday to Thursday. That was up from 60 per cent in late 2013 and late 2014.
Collins' proposal likely would be offered in the Republican-led Senate sometime next week, provided the four other gun-control proposals fail to pass on Monday.
A senior Democratic aide said that Democrats have concerns that under Collins' bill, people credibly suspected of involvement in terrorism would not be covered by the weapons ban.
Collins told reporters on Thursday that barring people on terrorism watch lists from weapons purchases carried with it the risk of affecting people who have been swept onto the lists without good cause.
"What we're trying to do is not deny constitutional rights to a large group of individuals" who find themselves on watch lists despite the fact that there might not be credible evidence of potential criminal intentions, Collins said.