Senators gave Barack Obama a huge political boost on Thursday by passing a sweeping remake of the US health care system that aims to extend coverage to 31 million uninsured Americans.
Vice President Joe Biden presided over the early morning Christmas Eve ballot in which 58 Democratic senators and two independents gave Obama the 60 votes he needs to pass the bill.
The legislation must now be reconciled with a separate House of Representatives version before going to Obama's desk to be signed early next year.
Obama pledged in a television interview Wednesday that he would "absolutely" take a hands-on role in the reconciliation process in coming weeks.
"We hope to have a whole bunch of folks over here in the West Wing, and I'll be rolling up my sleeves and spending some time before the full Congress even gets into session," he said on PBS.
The final Senate vote had been planned for late Thursday, but leaders in the upper chamber agreed to let weary staff and lawmakers go home earlier for the holidays as ice storms headed for the Midwest.
After the vote, attention narrowed on negotiations to forge a compromise between the final Senate bill and the House version, approved on November 7.
They differ on several points, and Obama allies have openly stated preferences for key chunks of the House version, setting up potentially damaging Democratic in-fighting ahead of crucial 2010 mid-term elections.
The headline battle looms over the provision of a government-backed "public option" to compete with private insurers. This measure was stripped from the Senate bill but remains in the House version.
Another bone of contention is the House bill's tougher restrictions on federal funds subsidizing abortions: while pro-choice lawmakers denounce the limits, centrist Democrats say they will withhold support without them.
Centrist senators have also warned that they will doom the measure if the compromise talks lead to drastic changes to the Senate's hard-won compromise.
Obama, conscious of how much political capital he has invested in this issue, at which generations of his predecessors have tried and failed, insists the Senate bill contains most of what he wants.
"I'd say we did really well," he told National Public Radio on Wednesday.
"I actually think that, considering how difficult the process has been, this is an end product that I am very proud of and is greatly worthy of support."
Obama acknowledged that the Senate's decision to do away with the public option has bitterly disappointed some liberals, but insisted the reform would be meaningful.
"This notion, I know, among some on the left that somehow this bill is not everything that it should be... just ignores the real human reality that this will help millions of people and end up being the most significant piece of domestic legislation at least since Medicare and maybe since Social Security," he said.
On Monday, Obama sought to rebut critics who say the United States cannot afford the 10-year, nearly one-trillion-dollar program to extend coverage to 31 million of the 36 million Americans who lack it now.
He pointed to estimates from the Congressional Budget Office (CBO), which found the bill would reduce the federal deficit by 132 billion dollars over the first 10 years and as much as 1.3 trillion in the next decade.
The United States is the world's richest nation but the only industrialized democracy that does not provide health care coverage to all of its citizens.
As a nation, the United States spends more than double what Britain, France and Germany do per person on health care.
But it lags behind other countries in life expectancy and infant mortality, according to the Organization for Economic Cooperation and Development (OECD).