The US House of Representatives has taken the most critical step yet toward adoption of legislation to overhaul the nation's health care system, The New York Times reports.
By a vote of 224-206, the House approved the key procedural measure necessary to pass the legislation.
After days of hard-fought negotiations, Obama pledged to sign an executive order reaffirming a longstanding US ban on government funding for abortions, winning support for the bill from a group of conservative Democratic holdouts.
"I've always supported health care reform," said the group's leader, Democratic Representative Bart Stupak, flanked by other anti-abortion lawmakers.
"This bill is going to go through."
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The breakthrough on Sunday made it all but certain that Obama's Democratic allies had locked down the 216 votes needed to ensure passage of the sweeping legislation over united Republican opposition in a ballot expected late in the day.
"We're well past 216," boasted Stupak, who spoke to reporters moments after White House communications director Dan Pfeiffer said Obama would decree that "restrictions against the public funding of abortions cannot be circumvented."
Obama's plan, a compromise between rival House and Senate versions of the bill passed last year, would bring the world's richest country closer than ever in its history to guaranteeing health care coverage to all its citizens.
Using a blend of expanded government health programs and subsidies for millions to buy private insurance, the bill would add some 32 million Americans to the ranks of those covered for a total of 95 per cent of Americans.
The White House said Obama planned to make a televised statement after the House vote, on which he has staked his effectiveness and political legacy.
Frustrated Republicans, united in opposition to the bill, said they would keep up the fight against the measure, which would usher in the most sweeping overhaul of its kind in four decades.
Republicans assailed the proposal in often bitter debate on the floor of the House and took turns encouraging hundreds of protesters outside the Capitol, holding up signs that read "Kill The Bill" and loudly chanting that slogan.
"In November, we'll remember," the demonstrators chanted, a reference to mid-term elections to decide control of the Congress.
Inside, Republican Representative Paul Ryan levelled angry charges that the legislation would crush the free market in the heavy hand of government while raising taxes and creating a bevy of inefficient agencies.
"This bill is a fiscal Frankenstein," he said. "It's not too late to get it right, let's start over, let's defeat this bill."
Republicans also vowed to keep up the fight in the Senate - the next battleground - and repeal the broadly unpopular bill if they win back majorities in November.
The Democratic plan called for the House to approve the Senate version of the legislation, sending it to Obama to sign into law, then pass a package of "fixes" to make it more like the House-passed health care bill.
The Senate would then take up the changes and approve them separately, under rules that prevent Republicans from using a parliamentary tactic, the filibuster, to indefinitely delay and therefore kill the measure.
Senate Republicans plan to besiege the legislation with "hundreds of amendments," to "highlight what is in the bill that is bad," one of their leaders, John Cornyn, told Fox News.
Cornyn acknowledged that Vice President Joe Biden, the Senate's presiding officer, could declare the amendments to be purely delaying tactics and call a vote on the legislation.
"I guarantee it will happen on television ... for 300 million people to see and I think there will be a terrible price to be paid for this sort of defying public opinion," said Cornyn.
Recent public opinion polls have painted a confusing picture, with respondents expressing strong support for individual elements of the bill, but with large numbers saying they oppose the overall measure.
Democrats have highlighted the independent Congressional Budget Office's estimate that the bill would cost 940 billion dollars over the next 10 years, while cutting 143 billion dollars from the bloated US deficit through 2019 and 1.2 trillion over the following decade.
The House vote on what Obama has called "the toughest insurance reforms in history" would come a century after president Theodore Roosevelt called for a national approach to US health care.
Before the final showdown, Democrats won a series of procedural votes by margins of 228-195, 230-200, 228-202, and passed a "rule" governing the debate in a 224-206 vote.
