President Bush, eager to sign the bill and promote it on the campaign trail, praised the action in a statement and in his radio address broadcast hours after the vote. "We're on the verge of success" of modernizing and strengthening Medicare," he said.
As the Senate began its debate, Mr. Bush appealed for final passage. "I urge all members of Congress to remember what is at stake, and to remember the promise we have made to America's seniors," he said.
Sen. Jon Kyl, R-Ariz., a conservative who said he would reluctantly vote for the legislation, led off the discussions by saying, "This is a historic day."
It was that, and more, in the House, where passage by a 220-215 vote capped an extraordinary roll call that began at 3 a.m. It consumed nearly three hours before the GOP leadership could overcome a rebellion by conservatives in their own ranks and the overwhelming opposition of Democrats.
"In the end, democracy works," said Rep. David Hobson, R-Ohio, as weary Republicans marked their overtime victory.
"We won it fair and square and they stole it by hook and crook," countered House Democratic leader Nancy Pelosi of California.
In the Senate, supporters expressed growing confidence they would prevail. The measure would give 40 million older and disabled Americans a prescription drug benefit and a new option for private health care coverage.
"After this legislation goes into effect, low-income seniors will never be confronted with the choice of putting food on the table or paying for lifesaving prescription drugs," Speaker Dennis Hastert, R-Ill., said well after midnight, just before the lights dimmed in the chamber to signal the beginning of the longest roll call in the history of the House.
But Pelosi said older Americans know that her party gave birth to Medicare during the Great Society. "We want to protect it and strengthen it. America's seniors have also known where Republicans stand, for four decades they have waged war on Medicare," she said.
The bill represented a political compromise of sorts - the new prescription drug benefit, coupled with federal subsidies designed to give private insurance companies incentives to establish new managed care plans around the country.
Republicans said these new plans, either preferred provider organizations or HMOs, would modernize Medicare, offering better coverage at lower cost. Democrats expressed skepticism, saying the plans marked the first step on the road toward privatization.
Dozens of lawmakers, participants and spectators both, waited out the drama of the middle-of-the-night roll call. Hastert, his lieutenants and Health and Human Services Department Secretary Tommy Thompson shuttled from one GOP holdout to another seeking enough votes to prevail.
White House spokeswoman Suzy DeFrancis said Mr. Bush lobbied about a dozen lawmakers by phone from the White House late Friday and early Saturday.
CBS News Correspondent Mark Knoller reports not all of them changed their minds, but in the end, the president got the vote he wanted.
The vote was stuck at 216 to 218 for over an hour, and the bill appeared on the verge of defeat, before a flurry of last-minute switches.
"I did not want to vote for this bill," said Rep. C.L. (Butch) Otter, R-Idaho. He did, one of a handful of late GOP converts. He said afterward he became convinced that if the measure were defeated, another one would come back to the House floor even less to his liking.
The bill drew the support of 204 Republicans and 16 Democrats, many of whom waited until the bill appeared on the verge of passage in the final moments of the roll call before swinging behind it. Voting no were 189 Democrats, 25 Republicans and 1 independent.
Nearly 20 hours earlier, Republicans projected confidence, even bravado. "I look forward to the presidential signing ceremony," said California Rep. Bill Thomas, a key architect of a measure making the most sweeping changes in Medicare since the program's creation in 1965.
But that was before the near-solid wall of Democratic opposition, the stubborn refusal of conservatives to bend, the hours of debate, the behind-the-scenes lobbying, the presidential phone calls from Air Force One and the still-undisclosed deals made to secure passage.
"You'd think we were talking about different bills from the rhetoric we've heard this evening," said Rep. Deborah Pryce, R-Ohio, as the debate unfolded Friday night.
There was no disputing that.
"This is a defining issue," said Rep. Jim McGovern, D-Mass., as he made a case for rejecting the measure. "This bill is a huge giveaway to the prescription drug companies. And worst of all, this bill shoves Medicare down that path toward privatization."
"This bill is really all about a fair deal," countered Thomas, the chairman of the House Ways and Means Committee. "Modernize Medicare with prescription drugs, but put Medicare back on a sound financial basis as well."
As written, the legislation would virtually remake Medicare.
For the first time, older Americans earning more than $80,000 a year would be required to pay a higher premium for their Part B non-hospital coverage under Medicare.
For the first time, the legislation would also require those older Americans with annual incomes over $80,000 to pay higher premiums under Medicare Part B, which covers services outside the hospital. Additionally, it would establish new tax-preferred health accounts, open to individuals with high-deductible insurance policies.
The tax provision and the requirement for higher premiums were part of an effort to appeal to conservatives who favor transforming Medicare and restraining its cost, yet find creation of the new prescription drug benefit distasteful.
Many Democrats argued that some of the conservative-backed elements of the bill were too dear a price to pay for the drug benefit - particularly a provision creating a limited experiment in direct competition between private plans and traditional Medicare beginning in 2010.
Conservatives said just the opposite.
Rep. Tom Feeney, R-Fla., fielded an afternoon phone call from Bush, who was flying home from England aboard Air Force One. "I basically said it was a matter of principle, that I came to Washington not to ratify and to expand Great Society programs," said the first-term lawmaker. "He wasn't happy to hear that."