Updated: 3:46 p.m.Sen. Blanche Lincoln (D-Ark.) announced Saturday afternoon that she would provide the 60th vote Democrats need to start debate on a major health care reform measure. “Although I don’t agree with everything in this bill, I have concluded that I believe it is more important that we begin this debate to improve our nation’s health care system for all Americans rather than just simply drop the issue and walk away,— Lincoln said on the Senate floor Saturday afternoon.Still, Lincoln stated emphatically that she does “not support the creation of a so-called government-administered public plan,— and she threatened to stall debate at a later time if the public insurance option is not removed from the bill. Of three centrist Democrats who had wavered on whether to allow the bill to come up in the Senate, Lincoln was the last. Just hours before Lincoln’s announcement, Sen. Mary Landrieu (La.) said she would vote to end a filibuster, while Sen. Ben Nelson (Neb.) telegraphed his support for the procedural vote on Friday. All three have expressed concerns about a provision in the bill that would create a public option, albeit one that states could opt out of. Republicans, whose united front of 40 Members is insufficient to mount a filibuster, had hoped to attract the support of one of the three to block the bill from being debated or amended on the Senate floor. The vote, which is scheduled for 8 p.m. Saturday, will be on whether to break a filibuster of the motion to proceed to the bill. Lincoln, who could face a tough re-election next year and has been under increasing pressure in Arkansas to support a filibuster, addressed the political pressures facing her in an unusually frank floor speech. Lincoln acknowledged that interest groups have spent more than $3 million on ads in her state to try to persuade her to vote one way or another – or face defeat next year in her re-election race. “These outside groups seem to think this is all about my re-election. I simply don’t think they know me very well,— Lincoln said. “I am focused on my opportunity to influence the final version of health care reform legislation in a way that most helps my state.— She added that she is determined to resist pressures from both the right and the left.“I will not allow my decision on this vote to be dictated by pressure from my political opponents nor the liberal interest groups from outside Arkansas that threaten me with their money and their political opposition – the multitudes of e-mails and ads that we have received, unbelievable types of threats about what they’re going to do and how they’re going to behave,— she said.Lincoln already voted for the Senate Finance Committee bill when the panel considered it in September and October, but that measure did not include a public option.Earlier this fall, Lincoln wrote a public letter to Senate Majority Leader Harry Reid (D-Nev.) asking him to wait 72 hours after unveiling his bill before calling the vote. The lateness of Saturday’s vote is largely due to the fact that Reid unveiled the bill at 8 p.m. Wednesday. Landrieu credited Lincoln with helping to secure the three-day wait to review the bill.