WASHINGTON – A cornerstone of President Barack Obama’s drive to check gun violence is gathering bipartisan steam as four senators, including two of the National Rifle Association’s congressional champions, privately seek compromise on requiring far more firearms purchasers to undergo background checks.

The talks are being held even as Obama’s call to ban assault weapons and high-capacity ammunition magazines, the two other major pillars of his plan, are hitting rough waters on Capitol Hill. An agreement among the four senators to expand background checks would add impetus to that high-profile proposal by getting the endorsement of the bipartisan group.

“We’ll get something, I hope. I’m praying for it,” said Sen. Joe Manchin, D-W.Va., one of the participants.