US senators Wednesday announced a landmark bipartisan compromise that would expand background checks to all commercial firearm sales, in what could result in the most ambitious change to American gun laws since 1994.
The deal comes four months after the Connecticut school massacre that took the country's epidemic of gun violence to an alarming new level. Twenty small children were slaughtered by a deranged shooter, as were six staffers.
The amendment would see background checks -- the core of President Barack Obama's push for stronger gun safety measures -- expanded to include all sales made at gun shows and on the Internet, said the deal's architects, Democrat Joe Manchin and Republican Pat Toomey.
"We have an agreement... on an amendment to prevent criminals and the mentally ill and insane from getting firearms," Manchin, from the pro-gun state of West Virginia, said as he unveiled the measure.
Toomey, from Pennsylvania, where several rural communities support gun rights, appeared to poke a hole in the argument that any gun safety measures should be viewed as an infringement of the constitutional right to bear arms.
"I don't consider criminal background checks to be gun control," said Toomey, who like Manchin is a gun owner and avid hunter.
"I think it's just common sense. If you pass a criminal background check, you get to buy a gun."
Their amendment, crafted with the help of veteran Senate Democrat Chuck Schumer from New York as well as Republican Mark Kirk from Illinois, where the largest city Chicago is awash in gun violence, stops short of the universal background checks sought by Obama in the aftermath of Newtown.
Specifically, it would not affect person-to-person sales, such as those between relatives, with Manchin assuring that "personal transfers are not touched whatsoever."
But the legislation would strengthen existing law, which currently only requires background checks when guns are purchased from a licensed dealer.
And Toomey sought to ease existing worries that the background checks could lead to a national registry of gun owners, saying the proposed legislation "does not require record-keeping by any private citizens."
The Senate Democratic leadership has already introduced a three-part bill that would require expanding background checks to virtually all gun sales, make gun-trafficking a felony, and boost funding for school safety.
Majority Leader Harry Reid has scheduled a showdown vote on those measures for Thursday.
He has also said he would allow lawmakers from both parties to introduce amendments to the overarching legislation, and the Manchin-Toomey compromise would likely be introduced as such an amendment.
A group of 13 Senate Republicans vowed to obstruct the broader bill, but by late Tuesday that effort was weakening, with several other Republicans signaling they would vote for moving ahead with the bill.
Republican backing for any gun legislation is crucial for the measures to pass Congress, especially the Republican-led House.
Manchin said that in crafting the compromise he spoke with senators close to the gun issue from both parties, as well as rights organizations, gun-control advocates, and the National Rifle Association, which opposes the universal background checks sought by Obama.
Toomey said he was hopeful the bill could get sufficient Republican support in the Senate, and it had backing from a "substantial number of House Republicans" as well.
House Speaker John Boehner promised to consider any gun bill that passes the Senate.
"It's one thing for two members to come to some agreement," Boehner said. "That doesn't substitute the will for the other 98 members, and so we'll wait and see what the Senate does."
Expanding background checks enjoys sweeping public support, with polls showing about nine in 10 Americans in favor.
The checks are seen as far more viable than an assault weapons ban backed by Obama and some Democrats, which appears doomed in Congress.