"I don't consider criminal background checks to be gun control," said Toomey. "I think it's just common sense."
The deal dramatically improves the odds that the Senate will pass gun legislation with background checks, and puts right-wing Republicans in the position of deciding whether to filibuster an idea with overwhelming public support -- and, now, bipartisan Senate support.
"There are a number of gun control proposals that I think would actually infringe Second Amendment rights," Toomey said. "I will tell you categorically that nothing in our amendment prevents the ownership of guns by any lawful person, and I wouldn't support it if it did."
The legislation gives the FBI background check no more than 48 hours to block a sale at a gun show and aims to reduce that to 24 hours in four years. It requires the FBI to prioritize finalizing background checks at gun shows over storefront dealerships. The bill also allows interstate handgun sales from dealers.
The National Rifle Association immediately reacted to the announcement. The organization did not address the specifics of the Manchin-Toomey legislation but reasserted that it doesn't believe background checks are effective at preventing gun violence.
"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 group said in a statement after the bill was unveiled. "While the overwhelming rejection of President Obama and Mayor Bloomberg's 'universal' background check agenda is a positive development, we have a broken mental health system that is not going to be fixed with more background checks at gun shows."
The aim of the proposal, Manchin said, is "to keep guns out of dangerous hands and keep our children safe," but which protects Second Amendment rights of law abiding gun owners. "All personal transfers are not touched whatsoever."
The two senators also thanked Sens. Mark Kirk (R-IL) and Chuck Schumer (D-NY), who have also worked to reach a compromise on the issue.
"The events at Newtown changed us all," said Manchin. "It changed our hearts and minds. This amendment will not ease the pain of the families who lost that children on that horrible day. Not one of us in this great capital of ours with a good conscience could sit by and not try to prevent a day like that from happening again."