The US healthcare bill which is in the focus currently would need some major changes before it is approved by the democratic allies , US senators said.
A knife-edge ballot Saturday saw Democrats scrape the 60 votes needed for debate to begin November 30, but wavering senators Joe Lieberman and Ben Nelson sent a strong message that they would not back the bill as it stands.
Lieberman, an independent senator from Connecticut who usually votes in line with the Democrats and did so on Saturday, opposes the creation of a government insurance program to compete with private firms, the so-called "public option."
"We have a health care system that has real troubles, but we have an economic system that is in real crisis," said Lieberman, who fears the government program would be too expensive for the cash-strapped US economy.
"I don?t want to fix the problems in our health care system in a way that creates more of an economic crisis," he told NBC's "Meet the Press."
The US Thanksgiving holiday week was to be marked by bitter debate over the fine details of the bill, from its costs in terms of tax increases and fees to the merits of the "public option."
Divisive issues such as abortion funding could also come to the fore while some Democrats may also seek funding for pet causes in their states in return for passing what amounts to the biggest shake-up of US health care in four decades.
The leading Democrat in the Senate, Harry Reid, faced three possible defectors in addition to Lieberman, any one of whom could have deprived him the 60 votes necessary to prevent Republican parliamentary delaying tactics.
Those senators Mary Landrieu of Louisiana, Blanche Lincoln of Arkansas, and Nelson of Nebraska have signaled a willingness to join Republicans if their proposed changes to core provisions of the bill are defeated.
Before falling into party line on Saturday, Landrieu and Lincoln repeated their strong opposition to the "public option."
Nelson indicated Sunday that he could be persuaded on the issue, although he prefers that states be allowed to choose if they could join the program, rather than having to opt out.
"We could negotiate a public option of some sort that I might look at, but I don't want a big government, Washington-run operation," he told ABC television.
Nelson has also demanded tougher restrictions on federal money subsidizing abortions, mirroring language the House of Representatives added to its version of the bill when it approved it in a 220-215 squeaker November 7.
Democrat Charles Schumer, speaking on CBS, appeared confident that the bill would pass. "The wind is at our back," said the New York senator.
"There is no intent for it to compete unfairly with private insurance," Schumer said. "This is a modest public option."
The New York Times reported that the Obama administration was continuing to court two moderate Republican senators from Maine, Susan Collins and Olympia Snowe, hoping to win them over and break up the united Republican opposition on health care.
Debate in the Senate is expected to last at least three weeks, but Republicans hope to kill the bill or delay the battle into next year with the expectation that the 2010 midterm elections may make it harder for moderate Democrats to support it.
Senators voted 60-39 Saturday to formally start debate on legislation aimed at extending coverage to some 31 million Americans.
As well as the public insurance option, the Senate bill includes restrictions on dropping care for pre-existing ailments. It is estimated to cost 848 billion dollars through 2019, but cut the sky-high US budget deficit by 130 billion dollars over the same period.
A successful final vote -- expected a month away at the earliest -- would force the Senate and the House of Representatives to reconcile their rival versions of the bill and vote again on whether to send it to Obama.
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, about 36 million of whom are uninsured.
Several US presidents since Theodore Roosevelt in the early 1900s have sought to overcome the traditional US suspicion of a wider government role in health care.
The United States spends more than double what Britain, France, and Germany do per person on health care, but lags behind other countries in life expectancy and infant mortality, according to the Organization for Economic Cooperation and Development