A breakthrough agreement to expand background checks for gun buyers, announced on Wednesday by two US senators, boosts the prospects the Senate will approve at least some of President Barack Obama's proposed gun restrictions.
The deal by Democrat Joe Manchin of West Virginia and Republican Pat Toomey of Pennsylvania set the stage for a Senate debate on a gun-control bill that started on Thursday, when the Democratic-led chamber is expected to defeat conservative Republicans' efforts to block it from reaching the floor.
Many hurdles remain, including weeks of expected debate in the Senate and amendments that could make the bill unacceptable to some senators who now support it. Any gun-control measure that clears the Senate also is likely to get a cool reception in the Republican-led House of Representatives.
Even so, the proposal for expanded background checks appears to be Obama's best hope for meaningful gun-control legislation in the aftermath of the December massacre of 20 children and six adults at an elementary school in Newtown, Connecticut.
The tragedy in Newtown was a driving force behind Wednesday's agreement, which would expand criminal background checks of gun buyers to include sales made at gun shows and online.
As part of an intense campaign for gun restrictions, Obama brought 11 family members of Newtown victims to Washington this week for a series of emotional, face-to-face meetings with lawmakers.
Manchin choked up during a meeting with eight of the family members in his office Wednesday afternoon, breaking into tears when asked what their visit meant.
"I'm a parent, I'm a grandparent. ... I can't imagine this," he said before stopping and wiping his eyes with tissues.
The background check system advocated by Manchin and Toomey, both ardent defenders of gun rights, would close a major loophole in a system that analysts say allows as many as 40 percent of gun buyers to avoid checks.
But the agreement, designed to keep guns out of the hands of dangerous criminals and the mentally ill, has significant exemptions for "temporary transfers" of weapons or private sales among friends and family members. No background checks would be required in such transactions.
One question surrounding the compromise is whether some gun sellers could try to avoid doing background checks by saying that buyers were "friends."
More controversial parts of Obama's gun-control plan - such as a ban on rapid-firing "assault" weapons like the one used in Connecticut and limits on the capacity of ammunition magazines - appear to have a slim chance of clearing the Senate.
Obama praised the Manchin-Toomey deal in a statement, but said that "a lot of work remains. Congress needs to finish the job."
Obama's Democrats control 55 of the 100 Senate seats, but several, like Manchin, are strong supporters of gun rights.
"I'm looking forward to the debate. I'm hopeful, but I think this is a fluid situation," Toomey said at a news conference with Manchin.
The delicate nature of the upcoming Senate debate was evident on Wednesday when Toomey said he still might vote against the background check compromise if it is part of a bill with other amendments that Toomey believes would infringe on gun owners' rights.
"Today is just the start of a healthy debate that must end with the Senate and House hopefully passing these common-sense measures and the president signing them into law," Manchin told reporters.