Updated at 2:15 p.m. ET
A pair of bipartisan senators on Wednesday announced they've reached an agreement over a bill to expand background checks for gun sales, marking a significant first step as Congress attempts to tackle the thorny issue of gun control. While the Senate is now one step closer to actually voting on the legislation, the bill's fate remains far from certain, its authors acknowledged.
"I think this is a fluid situation, and it's hard to predict," said Sen. Pat Toomey, R-Pa., one of the drafters of the background check bill, said of the legislation's chances. He added, however, that the legislation represents common ground and that he's "hopeful" it can pass.
"Criminals and the dangerously mentally ill shouldn't have guns," Toomey said. "I don't know anyone who disagrees with that premise."
Toomey and Sen. Joe Manchin, D-W.Va., told reporters Wednesday that they have reached an agreement with Sens. Mark Kirk, R-Ill., and Chuck Schumer, D-N.Y., on the legislation, which would expand background checks to cover firearm sales at gun shows and over the Internet. When the Senate votes this week to begin debate on gun legislation, their bill will be the first amendment up for consideration, Manchin said.
The push for new measures to reduce gun violence was sparked by the December shooting in Newtown, Conn., which Manchin said "changed us all."
"This amendment won't ease the pain... but nobody here, not one of us in this great capital of ours in good conscious could sit by and not try to prevent a day like that from happening again," he said.
Manchin and Toomey both receive high marks from the National Rifle Association, which should help make their legislation more palatable to both Democrats and Republicans concerned about looking soft on Second Amendment rights. Of all the proposals up for consideration, expanding background checks may have the best chance of passing because of the overwhelming public support behind the idea.
"I don't consider criminal background checks to be gun control -- it's just common sense," Toomey said. When asked whether he was concerned about losing his strong rating from the NRA, he said, "What matters to me is doing the right thing, and I think this is the right thing." The senator added that most Pennsylvanians would agree with him.
Manchin said, "Back home where I come from, we have commonsense, we have nonsense and we have gun sense."
Soon after Manchin and Toomey announced their agreement, the NRA released a statement in opposition to it. "Expanding background checks at gun shows will not prevent the next shooting, will not solve violent crime and will not keep our kids safe in schools," the statement said. "The sad truth is that no background check would have prevented the tragedies in Newtown, Aurora or Tucson."
Though the background check bill will be the primary piece of legislation up for a vote before the Senate, another pair of bipartisan senators announced they have reached an agreement -- with the blessing of the NRA -- over another proposal to crack down on illegal gun trafficking and straw purchasing. Sens. Patrick Leahy, D-Vt., and Susan Collins, R-Maine, said they won NRA support for the Stop Illegal Trafficking in Firearms Act after making modifications, including language to ensure that lawful gun purchasers can buy firearms to give as bona fide gifts.