WASHINGTON - President Barack Obama, his top domestic priority in the balance, was to make a rare in-person plea Saturday for wary lawmakers to cast an historic vote for legislation to remake US health care.

Obama, who wooed skittish fellow Democrats by telephone Friday, hoped to bring the full persuasive power of the presidency to bear in an 11th-hour push to secure the 218 votes needed to prevail in the House of Representatives.

"The sales pitch is simply that we're on the cusp of the type of health care reform that this country has been talking about for decades," said White House spokesman Robert Gibbs. "Do this for the country. Do this for your constituents."

Democratic leaders set the stage for a final vote late Saturday on the 10-year, 900-billion-dollar measure, the most ambitious overhaul of its kind in a half-century, but said Republican delaying tactics could stall the process.

Democratic House Majority Leader Steny Hoyer said that he did not have the votes but was "very close," and added that he had cautioned lawmakers the final ballot may be pushed to Sunday, Monday, or Tuesday.

Democrats wrestled late Friday with an intra-party feud over whether government monies would go to funding abortions, after dispatching another dispute over ensuring that undocumented immigrants did not gain new benefits.

Republicans vowed to stay united in opposing the measure and hoped to peel off the more than 40 swing-vote Democrats they need to defeat the legislation, which would deal a severe blow to prospects for a health care overhaul.

Republicans said any postponement of the vote would reflect Democrats' inability to wrangle the support needed to pass the bill within their self-imposed timetable.

House Minority Leader John Boehner said the grim news that US unemployment had soared to 10.2 percent, the highest level since 1983, showed the need to defeat "this job-killing bill."

Even if Democrats squeeze the measure through, it must still clear the Senate, where Democratic Majority Leader Harry Reid faces more daunting obstacles and has hinted any action could slip to 2010.

That would put the issue front-and-center in the 2010 mid-term elections, when one third of the Senate, the entire House of Representatives, and many US governorships are up for grabs.

The United States is the only industrialized democracy that does not ensure that all of its citizens have health care coverage, with an estimated 36 million Americans uninsured.

And Washington spends vastly more on health care -- both per person and as a share of national income as measured by Gross Domestic Product -- than other industrialized democracies, according to the Organization for Economic Cooperation and Development.

The United States spent about 7,290 dollars per person in 2007, more than double what Britain, France, and Germany spent, with no meaningful edge in the quality of care, and lags behind OECD averages in key indicators like life expectancy and infant mortality.

Under the White House-backed bill, Americans would have to buy insurance and most employers would have to offer coverage to their workers -- though some small businesses would be exempt and the government would offer subsidies.

The measure includes a government-backed insurance plan, popularly known as a "public option," to compete with the private insurance industry.

The non-partisan Congressional Budget Office says the bill, as written, would cut the budget deficit by about 100 billion dollars over 10 years while extending health care coverage to 96 percent of all Americans.