Senate Democratic negotiators scrambled late Friday to lock down the 60 votes needed to move health-care reform to a final vote, a process that must begin before midnight Saturday for Majority Leader Harry Reid to meet his self-imposed Christmas deadline. Much of Reid's attention was focused on Sen. Ben Nelson, Neb., the only member of his caucus viewed as a serious defection threat. Meanwhile, Republicans vowed to use every available procedural tactic to keep the debate from advancing. Nelson told reporters late Friday that he remained dissatisfied with abortion-related language in the $848 billion bill. But he also is seeking changes to benefit his home state while easing the bill's burden on factions of the health-care industry, including home health-care services and health-insurance providers. 'We're working on a lot of things,' Nelson said during a break in the talks. 'Whether we've decided anything or not, the answer is probably not.' Nelson left the Capitol Friday night after 11 hours of talks and said negotiations would continue Saturday morning. Sen. Charles Schumer, D-N.Y., a Senate leader helping to negotiate the bill, said of the Nelson effort, 'Ben has a lot of things he's concerned about.' 'He's not for major apple-cart changes in any place; he's just for specific things and they have to be talked through,' Schumer said. Democratic leaders said they are cautiously optimistic that Nelson's concerns could be resolved, allowing Reid to unveil a final bill on Saturday and begin the lengthy process of ending debate and holding a final vote, which could come at 7 p.m. Christmas Eve. But Nelson said he wouldn't heed the clock. 'I don't have a deadline,' he said. 'To me, you've got to get it right.' To meet many of Nelson's requests, Reid must find additional funding by trimming provisions in the bill or adding new revenue sources. The abortion issue is more difficult, requiring a series of complex legal calculations, all fraught with political peril. Sen. Robert Casey, D-Pa., who shares Nelson's opposition to abortion, offered revised language that could become the foundation of a compromise, and Nelson said further changes had been offered Friday night to the Casey proposal in an effort to resolve his concerns. Casey's proposal would segregate private funds from federal taxpayer subsidies on new insurance exchanges that the bill would establish for individuals who don't have access to employer coverage. State insurance commissioners would conduct annual audits to ensure that the funds were kept separate. According to a framework provided by Casey's office, the proposal also would provide 'conscience protections' that bar discrimination against an individual health-care provider or health-care facility because of its unwillingness to provide, pay for, provide coverage of, or refer for abortions. And it would remove provisions that would have required every exchange to provide at least one plan that covered abortions, and one that did not. But Nelson said he still had objections. 'I haven't seen language that's acceptable yet,' Nelson said late Friday. Partisan tensions in the Senate had stretched to a breaking point at 1 a.m. Friday, when Reid barely won the votes needed to bring debate to a close on a $626 billion defense spending bill. Republicans tried to filibuster the measure -- to delay health care, some said -- but the effort failed 63 to 33. According to several Democratic senators, Reid was stunned by Republican opposition to a bill that funds U.S. troops and all other defense activities, having cut a deal with some GOP senators to advance the legislation. 'Rarely have I seen such brazen irresponsibility,' Reid said on the Senate floor. 'And rarely have our nation's citizens received such little regard from their leaders.' Republicans countered that they had no other choice, arguing that Democrats were rushing the health-care bill through the Senate with little scrutiny. 'The majority leader has signaled that he will finally unveil the most significant piece of domestic legislation in modern history some time on Saturday -- and force a vote in the middle of the night about 36 hours later,' said Senate Minority Leader Mitch McConnell, R-Ky. 'This is outrageous.' 