AFP - President Barack Obama's Democratic allies in the Senate strove Friday to lock down the support to prevail in a landmark first test vote on his top domestic priority, remaking US health care.

"We are not assuming a thing. We are working hard to bring all Democrats together for the 60 votes necessary to proceed to this historic debate," Senator Dick Durbin, the party's Senate vote-counter, told reporters.

But there were signs of Democratic confidence that they would win a procedural vote Saturday on what would be the most sweeping overhaul of its kind in four decades, extending health care coverage to an estimated 31 million Americans at a price tag of 848 billion dollars through 2019.

Democrats needed 60 votes to be able to override any delaying tactics from Republicans and approve a resolution that would formally start the debate -- a hurdle shaping up as the legislation's biggest test to date.

But Democratic Senate Majority Leader Harry Reid was already pursuing a long-term strategy to win the broader battle by courting a handful of swing-vote, centrist lawmakers to vote in favor of the overhaul itself.

After next week's Thanksgiving holiday break, Reid will speak to individual senators to "make sure they each have some peace of mind about what the bill does and can support it, and if they have a concern, address it," said Durbin.

With the 100-seat Senate's 40 Republicans seemingly united against the overhaul, vote-counters focused on three centrist Democrats -- Mary Landrieu of Louisiana, Ben Nelson of Nebraska, and Blanche Lincoln of Arkansas, who faces a tough fight to keep her seat in the 2010 mid-term elections.

Senator Joseph Lieberman, an independent who often votes with Democrats, was also in doubt for the final bill.

Republicans stepped up their campaign against the bill, with Senate Minority Leader Mitch McConnell denouncing "a trillion-dollar experiment in government-run health care that raises premiums, raises taxes, and cuts Medicare," which covers the elderly.

"We've now had less than 48 hours to look through this 2,074-page bureaucratic nightmare," said McConnell.

"The Republican health-care reform bill is zero pages long, because it provides zero relief for the American people and the problems they face with health care today," said Durbin.

The House of Representatives approved its own trillion-dollar version of the legislation on November 7, squeaking through on a 220-215 margin only after toughening restrictions on federal funds subsidizing abortions.

The Senate version does not include that stricter language, and changes several other key provisions.

If, as expected, the House and Senate approve different versions, they would need to work out their differences and approve the same legislation to send to Obama to sign into law.

The United States is the world's richest nation but 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.