WASHINGTON, D.C. -- The Senate's top Democrat said Tuesday he will force a vote this week on whether to open debate on tougher gun laws, increasing pressure on legislators from both parties negotiating a possible compromise on a package that some Republicans have threatened to filibuster.
A GOP filibuster would mean Senate Majority Leader Harry Reid needs 60 votes on Thursday just to begin Senate consideration of the package based on proposals by President Barack Obama in the aftermath of the Newtown school massacre in December that killed 20 first-graders and six educators.
Obama has made gun measures a major focus of his second term agenda, holding events across the country to push for Congress to vote on the package.
He spoke Monday in Connecticut, the state where the Newtown shootings occurred, and Vice President Joe Biden made a similar call for action at the White House on Tuesday.
Reid told reporters he hoped to get a bipartisan deal before the procedural vote on Thursday.
Talks involving Democratic Sen. Joe Manchin of West Virginia and Republican Sen. Pat Toomey of Pennsylvania have focused on a compromise on expanding background checks of gun buyers.
Even without a breakthrough, Democrats may be able to get enough Republicans to vote with them to overcome a GOP filibuster.
At least five Republicans have publicly opposed the filibuster pledged by 14 of their Senate colleagues, including GOP leader Sen. Mitch McConnell of Kentucky.
Sen. Kelly Ayotte, R-New Hampshire, said Tuesday she favored opening debate on the bill as long as amendments can be offered, adding: "I think it's an important debate to have and I do not believe we should block the motion to proceed."
Reid needs only five Republicans to join the 55 senators in the Democratic caucus in overcoming a filibuster. However, some Democrats from conservative-leaning states could join the GOP procedural blockade.
"I haven't made a decision on that," said Sen. Mark Pryor, D-Arkansas, who indicated he would oppose the original Democratic package approved by the Senate Judiciary Committee but could accept a more limited compromise.
McConnell later told reporters his filibuster threat referred to the committee's proposal, indicating he also could be open to a compromise.
Without a compromise, a successful Republican filibuster would stop consideration of the gun legislation before any votes on specific provisions.
Obama's rhetoric has reflected the political uncertainty, with the president and his aides using increasingly personal language intended to shame Republicans into allowing public votes on measures that have public support but are fiercely opposed by the influential National Rifle Association.
"If senators don't have the guts to go on the record to vote how they feel on this issue ... that would be a shame and that would be a disservice to their constituents," White House spokesman Jay Carney told reporters on Tuesday.
At a later White House event intended to keep up the public profile of the issue, Biden said Republican efforts to block tougher gun laws showed they were in a "time warp" because public support on issues such as expanded background checks "has moved beyond where it was five, ten, even three years ago."