WASHINGTON - With a filibuster threat in the air, the gun control debate takes a personal turn today on Capitol Hill as the families of the Newtown, Conn., shooting implore members of Congress to revive legislation that has stalled nearly four months after the slaying at Sandy Hook elementary school.
A group of mothers and fathers of the victims came to Washington aboard Air Force One after President Obama sought to rally support for the gun control bills during a speech Monday in Connecticut. It is an effort by the White House to regain momentum for the gun measures.
"Find out where your member of Congress stands on this," Obama said. "If they're not part of the 90 percent of Americans who agree on background checks, then ask them why not."
Senate Majority Leader Harry Reid, D-Nev., has set a tentative deadline of later today for a compromise deal to be brokered on a key piece of the legislation on background checks. If an agreement is not reached, aides said, he will begin scheduling votes on the bills later this week.
Two senators -- Joe Manchin, a West Virginia Democrat, and Pat Toomey, a Republican from Pennsylvania, are working on a possible bipartisan compromise on background checks. The plan would allow close friends and family to be excluded from those background checks if they are selling or trading guns to each other.
But no formal meeting has yet been scheduled today between the two senators, aides said, and it remains an open question whether they will be able to come to an agreement that would have to gain support from at least 60 senators to move beyond a filibuster.
"Shame on them," Reid said in an impassioned plea on the Senate floor Monday, criticizing the efforts from more than a dozen Republicans who threatened to block a vote on the bill.
The Sandy Hook families, who are set to spend the day meeting with senators, face an uphill battle. A ban on so-called assault weapons and on high-capacity ammunition clips has already stalled. The strongest chance for a gun bill now revolves around requiring background checks for gun sales, perhaps by creating an exception for the private sale of guns to family members.
But there is movement on some parts of the gun debate, with Sen. Tim Kaine, D-Va., coming out today in support of an assault-weapons ban. He urged his fellow senators to not be afraid of the gun lobby, noting that he has been elected as governor and senator with the opposition of the NRA, which is based in his home state.
"It is important for me to remind my colleagues that you don't need to be afraid of them," Kaine said in an interview.
Senate Minority Leader Mitch McConnell, a Kentucky Republican who returns to Washington today, has vowed to join a group of Republicans to block debate on the gun bill. He and his party are walking a fine line, advisers say, on an issue as volatile as gun control, parts of which are supported by a majority of Americans.
The National Rifle Association has declined to comment on the possible compromise between Manchin and Toomey, with a spokesman telling ABC News that the substance of the exclusions on background checks must be examined.
The gun control debate will dominate the discussion on Capitol Hill this week, with Democrats eager to force the hands of Republicans and try to move to a roll-call vote on the measures. A disagreement is brewing among Republicans about the wisdom of blocking a vote on gun bills.
For more from ABC News, click here.