Is the National Rifle Association beginning to lose its clout?

Is the National Rifle Association – the political bulwark against any gun-control legislation – beginning to lose its influence?

It’s way too soon to declare the powerful NRA on the wane. Its approval is still eagerly sought by many lawmakers who tout their high ranking by the organization.

But in the wake of recent mass shootings that have shocked the nation, many gun-rights advocates – including many NRA members – are shifting in favor of stricter gun-safety measures.

The Washington Post reported Sunday that the Citizens Committee for the Right to Keep and Bear Arms, which boasts 650,000 members and supporters, is backing compromise legislation in the Senate that would expand background checks on gun buyers.

That proposal – put forth by Sens. Joe Manchin (D) of West Virginia and Pat Toomey (R) of Pennsylvania, both NRA members and gun owners – would expand background checks on firearms transactions at gun shows and for online sales.

“We decided to back it because we believe it is the right thing to do,” Julianne Versnel, the Citizens Committee’s director of operations, told The Washington Post.

So do most Americans, including most NRA members. According to a CBS/New York Times poll earlier this year, 92 percent of Americans and 85 percent of those living in a household with an NRA member support universal background checks on gun buyers. Other polls put NRA backers of background checks at about 75 percent.

In another development Sunday, Sen. Susan Collins, (R) of Maine, announced that she, too, will back the Manchin-Toomey proposal. (Earlier, Sen. Mark Kirk (R) of Illinois indicated his support for the compromise measure, which does not apply to gun exchanges between family members.)

"I grew up in Northern Maine where responsible gun ownership is part of the heritage of virtually every family,” Senator Collins explained in a statement. “I strongly support our Second Amendment rights, and two recent Supreme Court decisions … make clear that those constitutional rights pertain to the individual.”

“The Manchin-Toomey compromise takes a much more common sense approach [than tougher proposals] by requiring background checks only for commercial transactions and exempts family gifts and transfers,” she wrote. Like other senators, Collins said she was very moved by her meeting last week with the parents of children killed in the Sandy Hook Elementary School massacre in Newtown, Conn. (20 first-graders and six educators were killed Dec. 14, 2012).

On CNN Sunday, Sen. John McCain, (R) of Arizona – the state where former US Rep. Giffords was shot in the head in a January 2011 attack near Tucson in which six people were killed and 13 wounded – said he’s "very favorably disposed" to the compromise measure.

"I appreciate their work," Senator McCain said. "And the American people want to do what we can to prevent these tragedies.”

While the Citizens Committee for the Right to Keep and Bear Arms now backs the Manchin-Toomey compromise measure, the NRA continues to oppose it despite what appears to be support of the bill by most NRA members.

NRA executive vice president Wayne LaPierre says background checks are just the slippery slope toward a “universal registry of law-abiding people,” as he put it on Fox News recently. The Manchin-Toomey measure “will not prevent the next shooting, will not solve violent crime and will not keep our kids safe in schools,” the NRA asserts on its website.

It’s unclear whether that measure – indeed, any increase in gun controls – will make it through Congress.

“I think it’s an open question as to whether or not we have the votes,” Senator Toomey said on CNN’s “State of the Union” Sunday. “I think it’s going to be close.”

“We came here to do something,” Senator Manchin said during a joint interview with Toomey on CBS’s “Face the Nation.” “We’ve got a chance to make a difference in people’s lives. We have a chance to save lives and not infringe on law-abiding citizens of this country, gun owners like myself and Pat. We have that opportunity, and God help us if we don’t do it.”