Sen. Olympia Snowe announced Tuesday that she will vote for health care reform legislation before the Senate Finance Committee, becoming the only Republican to back the bill and virtually assuring passage out of the committee.

Snowe's support was the most sought-after Republican vote by Democrats for months. The Maine Republican could be the only member of her party to vote for health care reform, though she cautioned Tuesday that support for the committee bill does not guarantee support for a final product. 

"When history calls, history calls," she said, even though she had some criticism of the bill. 

She was among several key senators still on the fence over the pivotal package going into deliberations Tuesday, even though leadership aides said they were confident the bill would win enough backers. 

With 13 Democrats and 10 Republicans on the committee, the lone Republican vote helps Committee Chairman Max Baucus, D-Mont., hedge against any Democratic defections as well as claim some semblance of bipartisan support. 

But three previously undecided Democrats announced their support Tuesday, bolstering Baucus' majority on the panel. 

Sen. Ron Wyden, D-Ore., said Tuesday afternoon he would support the bill, despite concerns that it could increase costs for families with mandates to obtain coverage and inadequate subsidies. 

Sen. Blanche Lincoln, D-Ark., also announced her support, though adding the same warning that her backing is not guaranteed down the road. Lincoln had been concerned about the cost of the 10-year, $829-billion plan and has voted many times with Republicans to reduce taxes and penalties. She is a moderate Democrat in a red state staring at a potential conservative primary challenger. 

Sen. Jay Rockefeller, D-W.Va., was the last to unveil his support. The liberal Democrat wants nothing short of a government-run insurance plan in the bill, and he thinks the Finance Committee's "co-op" system is not sufficient. 

The road to the  Tuesday vote, however, has been paved with bickering and complaints. At the start of discussion, the top Republican on the Senate Finance Committee said that he's still concerned about the potential for more government control over health care. 

Sen. Charles Grassley's comments, and those of other Republicans, aired the lingering partisan divisions on the panel, even as Baucus stressed that his bill is a "balanced plan" that should win bipartisan support and eventually pass the full Senate. 

"With this markup nearing its conclusion, we can now see clearly that the bill continues its march leftward," Grassley, R-Iowa, said. 

Sen. Orrin Hatch, R-Utah, complained that the package would impose billions in new taxes. Sen. Jim Bunning, R-Ky., complained that 25 million people would still be uninsured despite the major changes. 

"This package is going in the wrong direction. Spending more and taxing more without covering more people," Bunning said.

But Baucus urged his colleagues to "make history" by sending his comprehensive overhaul to the floor of the Senate and one big step closer to the president's desk. 

"Now it's time to get the job done," chairman Baucus, D-Mont., said. "My colleagues, this is our opportunity to make history." 

The panel is the last of five to act on health legislation and has been the center of attention in deliberations for months. Tuesday's vote could mark the biggest advance so far toward health care reform, as the committee's legislation is considered the best building block for a compromise plan in the full Senate. 

Other Democrats defended Baucus' efforts at reaching a middle-of-the-road compromise, and blasted the insurance industry for releasing a critical report on the bill just hours before the committee convened. 

Sen. John Kerry, D-Mass., said the move was a "disgrace" and was a sign that a government-run insurance plan should eventually be enacted to keep the insurance industry in check. 

"It's a powerful argument for the attitude of an industry toward this effort," Kerry said. 

If the Finance Committee bill passes, President Obama's top domestic priority will have advanced farther than former President Bill Clinton's effort ever did. The Clinton health plan never made it through all the congressional committees with jurisdiction. 

The final days before Tuesday's long-anticipated vote were rocky. After playing nice for months, the health insurance industry released a report contending that the legislation would cause hefty increases in health insurance premiums. 

Democrats and their allies scrambled Monday to knock it down. "Distorted and flawed," said White House spokeswoman Linda Douglass. AARP's senior policy strategist, John Rother, called it "fundamentally dishonest." 

The drama threatened to overshadow the vote on the plan that Baucus has touted as the sensible solution to America's problems of high medical costs and too many uninsured. 

The bill includes consumer protections such as limits on copays and deductibles and relies on federal subsidies to help lower-income families purchase coverage. Insurance companies would have to take all comers, and people could shop for insurance within new state marketplaces called exchanges. 

Medicaid would be expanded, and though employers wouldn't be required to cover their workers, they'd have to pay a penalty for each employee who sought insurance with government subsidies. The bill is paid for by cuts to Medicare providers and new taxes on insurance companies and others. 

Unlike the other health care bills in Congress, Baucus' would not allow the government to sell insurance in competition with private companies, a divisive element sought by liberals. 

Last-minute changes made subsidies more generous and softened the penalties for those who don't comply with a proposed new mandate for everyone to buy insurance. The latter change drew the ire of the health insurance industry, which said that without a strong and enforceable requirement not enough people would get insured, and premiums would jump for everyone else.
America's Health Insurance Plans commissioned a study to prove just that, alleging the bill would add thousands of dollars to a typical policy. It was timed just ahead of the vote on Baucus' bill but the industry was already looking ahead to negotiations on a final package to bring to the Senate floor. 

Once the Finance Committee has acted, the dealmaking can begin in earnest with Reid, D-Nev., working with White House staff, Baucus and others to blend the Finance bill with a more liberal version passed by the Health, Education, Labor and Pensions Committee. 

A major question mark is whether Reid will include some version of a so-called public plan in the merged bill. Across the Capitol, House Democratic leaders are working to finalize their bill, which does contain a public plan, and floor action is expected in both chambers in coming weeks. 

If passed, the legislation would then go to a conference committee to reconcile differences. 

Fox News' Trish Turner and The Associated Press contributed to this report.