enlarge The Associated Press

Sen. Max Baucus, D-Mont., shakes hands with Sen. Olympia Snowe, R-Maine, on Capitol Hill in Washington on Tuesday. Sen. Orrin Hatch, R-Utah, is at center.

WASHINGTON — Sen. Olympia Snowe kept Democrats guessing until just before Tuesday's landmark health-care reform vote in the Senate Finance Committee.

"Is this bill all that I would want? Far from it," Snowe told committee colleagues. "But when history calls, history calls."

Snowe did call her Republican leader, Mitch McConnell of Kentucky, Tuesday morning to break the news about her plans.

For months, Obama had pursued her support in phone calls and meetings. Snowe could be the Democrats' 60th vote required to overcome Republican objections to the bill and give the final version the barest quality of bipartisanship.

"I want to particularly thank Senator Olympia Snowe for both the political courage and the seriousness of purpose that she's demonstrated throughout this process," Obama said Tuesday.

Republicans have for weeks grumbled about punishing Snowe should she vote "yes" at any stage of the lengthy process. One option long discussed: denying her the coveted senior Republican seat on the Senate Commerce Committee.

The best they could do publicly Tuesday was to make clear that she told them her decision before the Democrats found out and to keep communication open with her. Snowe, after all, might well be the sole Republican negotiator at the table when Reid hashes out a final measure for a Senate vote.

If so, she represents the GOP's best chance at winning votes on changes they want. But Snowe signaled that this could be a one-shot deal. "My vote today is my vote today. It does not forecast my vote tomorrow," the third-term senator said.

To keep her support for the bill, Snowe said, Senate Majority Leader Harry Reid, D-Nev., needs "to incorporate some of the ideas that have been mentioned (in the Finance Committee) – to make sure that we contain the cost, that it is budget-neutral."

Snowe pointed out the issue of a public- or government-run health care option was a "line of demarcation between Republicans and Democrats," implying that she would withdraw her support if such an option were included.

She also challenged insurance companies, which she said stood to "gain enormously" from the health care overhaul. "I think that the insurance companies have to step up to the plate and offer some constructive solutions," she said. "Twenty-nine million more Americans will be entering the system. That's 29 million more customers."