"I know this will be a tough vote," Mr. Obama said in remarks prepared for delivery at George Mason University in Fairfax, Va. "I know that Washington has treated this debate like a sport."
The House is racing toward an expected vote on the $940 billion health bill Sunday, with Democrats still searching for enough votes to assure passage.
Mr. Obama, who has been lobbying on-the-fence Democrats all week, said he's not sure what the political impact of the legislation—uniformly opposed by Republicans—will be. He canceled a planned trip to Australia and Indonesia to remain in Washington for the conclusion of the health-care debate.
"I'll confess—I don't know how this plays politically. Nobody really does," he said. "But what I do know what it will mean for America's future. I don't know what impact reform will have on our poll numbers. But I know the impact it will have on the millions of Americans who need our help."
Meanwhile, Democratic Rep. John Boccieri of Ohio said Friday that he is switching his vote to "yes." The freshman lawmaker opposed the House version of the bill last November.
On Thursday, the nonpartisan CBO said the bill would extend health insurance to 32 million Americans now without coverage, while reducing the budget deficit by $138 billion over 10 years. Democrats hailed the numbers and said they improved the odds of the bill's passage, while Republicans said the estimate includes unrealistic assumptions and predicted the new taxes in the bill to keep the deficit down would crimp the American economy.
The CBO number may persuade some lawmakers because it puts the 10-year cost of the bill below $1 trillion, a symbolic threshold many Democrats didn't want to cross. Perhaps more important is the estimate of how much the bill would cut the deficit.
Is it the end or the end of the beginning for the Obama administration's battle for passing health reform legislation? Janet Adamy reports on last minute deal-making that could lead to a vote on Sunday.
The focus was on a handful of conservatives who voted against the House version of the health overhaul in November but have been targeted as possible supporters as Democrats struggle to build the 216-vote majority needed for passage.
A few hours after release of the CBO report, one fiscal conservative, Rep. Bart Gordon of Tennessee, said he would vote for the legislation, a change from last fall. Rep. Gordon cited the deficit forecast, saying, "That's why I am supporting it."
Rep. Betsy Markey (D., Colo.) also said she planned to switch from no to yes. Democrats were still short of the votes they needed, but people familiar with the vote count said they appeared to have narrowed the gap.
Democratic leaders were closely monitoring Reps. Allen Boyd of Florida and John Tanner of Tennessee, both bellwethers among centrist Democrats. A spokesman said Mr. Tanner was reviewing the CBO report and hadn't made up his mind. Mr. Boyd, in a brief interview, said he also remained undecided, but called the latest assessment of the bill's budget impact an improvement. "Sounds better, doesn't it?," he said.
But one former yes voter, Rep. Steve Lynch of Massachusetts, said he wasn't persuaded, an indication of the many variables Democrat vote-counters must contend with.
Rep. Lynch, a liberal Democrat, said the package headed to floor is "not systemic reform." He voiced concern that a set of changes to the Senate bill that the House also plans to vote on might die in the Senate, as have dozens of other House bills. "My experience tells me this might be one more bill on the pile," he said.
House Republicans said they would work to stop the bill from passing. "We're doing everything we can to talk to colleagues across the aisle to say, 'This is really bad for America,'" said Eric Cantor, the House's No. 2 Republican.
Before the House will be two bills—the sweeping Senate-passed legislation and a smaller package of changes meant to bolster support in the House. Taken together, they will make the most significant changes to the U.S. health system since the creation the Medicare more than four decades ago.
The Senate-passed health bill would create a near-universal system of health insurance by expanding Medicaid, the federal-state insurance program for the poor, and giving tax subsidies to help low and middle-income individuals comply with a new government mandate that nearly all Americans carry insurance.
The legislation would prevent insurers from denying coverage to people because they have a pre-existing health condition or revoking their policies if they became ill. The smaller companion bill includes changes to the Senate bill to address House Democrats' concerns, including greater subsidies for lower earners to buy coverage.
With undecided members weighing how to vote, one senior Democrat—Energy and Commerce Chairman Henry Waxman of California —warned the party will pay a heavy price if the legislation fails. "Members who think they have a tough race are not going to find security in voting no," he said. "If this bill doesn't pass, they are going to be wiped out."