Obama urges Senate to pass health-care bill; Lieberman signals support President Obama urged Senate Democrats on Tuesday to overcome lingering disputes and push a health-care overhaul through the chamber before Christmas, as vigorous negotiations continued behind the scenes to lock down the last votes needed for final passage. Sen. Joseph I. Lieberman (I-Conn.), once a critic of the legislation, appeared to be warming to the $848 billion package after Senate leaders said they were ready to jettison a plan to extend Medicare coverage to uninsured people as young as 55, an idea Lieberman denounced over the weekend. He said Tuesday that he expects to support the bill if that provision is dropped. That would leave Sen. Ben Nelson (D-Neb.) as the only known holdout among the 60 lawmakers who caucus with Democrats. Senate leaders and White House officials were working hard Tuesday to convert the former Nebraska insurance commissioner, who has said he will not support the measure unless it bars the use of public money for abortion. The final negotiations followed months of debate and compromise on the administration's domestic centerpiece. Liberals fumed over the abandonment of a government-run insurance option, but they did not defect, and as a final vote neared, strenuous efforts to win the support of even a single Republican seemed increasingly unlikely to succeed. Emerging from a rare White House meeting with the Senate Democratic caucus, Obama said he is "cautiously optimistic" that Majority Leader Harry M. Reid (D-Nev.) will be able to unite the party, avoid a Republican filibuster and approve the 2,000-page package, which would come close to attaining the party's long-sought goal of universal medical coverage. "It's clear that we are on the precipice of an achievement that's eluded Congresses and presidents for generations, an achievement that will touch the lives of nearly every American," Obama told reporters afterward. There are still some differences that have to be worked on. This was not a roll call. This was a broad-based discussion about how we move forward. Yet even as Reid appeared to be closing in on his target, Senate leaders were weighing whether to take a break from the debate to act on a $626 billion measure to fund military operations. Under a schedule sketched out by senior aides, Reid could announce the final health-care compromise as soon as Wednesday, switch to the defense spending bill, then return to a crucial procedural vote on health care this weekend. The target for final passage is Dec. 23, aides said. That schedule would leave no time for negotiations with the House before the Christmas break, however, and House Majority Leader Steny H. Hoyer (D-Md.) confirmed Tuesday that the president probably will not get his wish of signing health-care legislation this year. "There's significant and important differences between what the Senate is proposing and what we proposed," Hoyer said, "and those matters will have to be discussed," most likely in a House-Senate conference committee in January. Compromises in the Senate have increased the distance between that bill and the House measure, and there were indications Tuesday that bridging the divide could be a challenge. Former Vermont governor Howard Dean, a powerful voice among liberals, said that "the best thing to do right now is kill the Senate bill" and start fresh. Meanwhile late Tuesday, the Senate dispatched with a series of amendments, turning back a Republican proposal to strip the bill of taxes that would break Obama's campaign promise not to increase levies on the middle class. The Senate also defeated a proposal by Sen. Byron L. Dorgan (D-N.D.) to allow Americans to import low-cost prescription drugs, a provision that could have upended a deal Obama made with drugmakers this year to support the health-care overhaul. The Dorgan amendment garnered 51 votes, short of the 60 needed for passage. In one of the few bipartisan votes in the health-care debate, 23 Republicans joined 27 Democrats and one independent in supporting the proposal, while 17 Republicans joined 30 Democrats and one independent in opposing it.