A healthcare reform programme being considered in Congress could cost one trillion dollars over 10 years, researchers at the US Congressional Budget Office (CBO) have estimated.
"Enacting the proposal would result in a net increase in federal budget deficits of about 1.0 trillion over the 2010-2019 period," the non-partisan CBO said in a letter to Senator Edward Kennedy, a Democratic stalwart who has spent much of his career pushing for an overhaul of the healthcare system.
But the CBO also cautioned that "those figures do not represent a formal or complete cost estimate for the draft legislation."
The proposal being hammered out by lawmakers has not yet been finalized, and the public funding aspect of healthcare reform backed by President Barack Obama and much of his fellow Democrats, is at the center of vigorous debate.
The president wants Congress to approve his proposal to overhaul healthcare by the end of the year in order to fulfill one his key campaign promises -- providing health care to the 46 million Americans, some 15 percent of the population, who currently don't have any medical coverage.
The White House is proposing a new "public" program to compete with private insurance plans many US workers obtain through their employers.
Obama on Monday warned that the country would go broke if healthcare reform is rejected, as he tried to convince skeptical doctors in Chicago of the merits of his government plan to equip all Americans with "affordable" health insurance.
"To say it as plainly as I can, healthcare is the single most important thing we can do for America's long-term fiscal health -- that is a fact," Obama told the annual meeting of the American Medical Association (AMA).
Senate Republicans meanwhile were staking out the ground for a confrontation, with one eye on mid-term congressional elections in 2010.
"Americans don't want a government-run system that puts bureaucrats between patients and doctors," said Mitch McConnell, the Senate's top Republican.
Obama's critics claim his reform plans would starve patients of choice, erode the quality of healthcare and saddle the industry with an inefficient new government bureaucracy.
Republican legislators have offered a draft proposal that would ban a public health care option.
"If we have a government option, then sooner or later it will dramatically increase the cost, it will crowd out private health insurance," Republican Senator John McCain told CNN.