Suddenly emerging as a national champion of gun control, U.S. Sen. Pat Toomey of Pennsylvania wanted to make it clear he isn't for gun control.

Appearing with Sen. Joe Manchin, a West Virginia Democrat, to announce an agreement on a proposal for strengthened background checks Wednesday, Toomey hurried to stake out his pro-gun turf.

"Pennsylvania has a long, bipartisan tradition of supporting gun rights, and I've been proud to be a part of that tradition," Toomey said early in his remarks. "I've got to tell you, candidly, I don't consider criminal background checks to be gun control. It's just common sense."

Toomey, a fiscal conservative who's focused on deficit spending, felt compelled to explain why he'd gotten into the gun issue at all. First, he said, it became apparent some gun measure would reach the Senate floor.

"It's not something that I sought, but something that I think is inevitable," Toomey said. "The second thing is, it became apparent that there are a number of gun control proposals that I think actually would infringe Second Amendment rights."

So, as Toomey explained it, he intervened to get the right kind of gun measure passed -- adding that this proposal actually expands protection of Second Amendment rights. He said it ensures, for example, that gun owners with carry licenses in one state won't face sanctions when transporting their weapons across state lines.

Spending political capital, compiling moderate credentials

Polls show broad support for background checks, and Muhlenberg College political scientist Christopher Borick said Toomey has amassed such political capital among conservatives that he can afford to spend a little accommodating moderates. 

"As he approaches his 2016 re-election bid, he's going to want to have some really solid pieces on his resume that speak to his moderate credentials," Borick said. This fits.

Asked if he's concerned about criticism from conservatives, Toomey said he's concerned about doing the right thing. He was unequivocal during a conference call with reporters later when asked about proposals to ban assault weapons and high-capacity magazines.

"I'd be strongly opposed to both of them," Toomey said. "Those are infringements on Second Amendment rights. I think they won't accomplish anything constructive, and I will vote no if there's an amendment to offer either one."

The NRA issued a statement condemning background checks without mentioning Toomey by name.

The Conservative group Heritage Action for America released a statement saying it expects better from Toomey, and his constituents will also.

CeaseFirePa issued a statement praising Toomey's action, and the group Mayors Against Illegal Guns has pulled TV ads aimed at Toomey.

The Bellevue, Washington-based Citizens Committe for the Right to Keep and Bear Arms issued a statement calling for universal background checks for elected officials.