The US House of Representatives has brought the federal government closer to a shutdown as it voted to delay President Barack Obama’s landmark health care law for a year as part of an emergency spending bill.
There is now less than 48 hours to avert a shutdown, which will begin on Tuesday if no spending bill is passed.
The Senate is not due to meet again until Monday afternoon.
In a statement issued on Sunday, US Senate Majority leader Harry Reid said that "after weeks of futile political games from Republicans, we are still at square one".
He added that Republican efforts to change the bill - that would delay the healthcare law for a year and repeal a tax on medical devices - were pointless.
At 11:59pm local time on Monday (03:59 GMT on Tuesday), the US government technically runs out of money to fund many of its programmes in the new fiscal year that starts on Tuesday, unless Congress can agree on a funding bill.
If Congress cannot come to a compromise by midnight on Monday, as many as 800,000 federal workers would be furloughed as part of a partial government shutdown.
Democrats in the Senate have already defeated one House proposal to derail the law, which is known to both sides of the debate as Obamacare, and Reid said they would do so again, calling the Republican move "pointless".
A Democratic aide said the Senate would "strip everything out" of the House measure and "send them back a clean bill".
Neither side wants to be the last to cast the final vote that would lead to a shutdown.
|The failure of the bill would close down much of the US government for the first time since 1996 [AFP]
While polls consistently show the American public is tired of political showdowns and opposed to a shutdown, House
conservatives were jubilant about the fight ahead.
"This is a win-win all the way around," said Arizona Representative Matt Salmon, who described the mood of Republicans as "ecstatic".
For good measure, Republicans said they would also approve a bill repealing a tax on medical devices that helps fund the healthcare law.
In an effort to signal their seriousness about a shutdown, as well as cover themselves from political fallout, Republicans said they would separately approve a bill to ensure that members of the US military continue to be paid if government funding is cut off.
In a government shutdown, spending for functions considered essential, related to national security or public safety, would continue along with benefit programmes such as Medicare health insurance and Social Security retirement benefits for seniors.
But hundreds of thousands of civilian federal employees - from people who process forms and handle regulatory proceedings to workers at national parks and museums in Washington - would be furloughed.
The healthcare law, set for launch on Tuesday, will provide insurance coverage for millions of uninsured Americans through exchanges.
'Tea Party extremists'
Republicans object strongly to Obamacare, calling it a massive and unnecessary government intrusion into medicine that will damage the economy.
The last government shutdown ran from December 16, 1995 to January 6, 1996 and was the product of a budget battle between Democratic President Bill Clinton and Republicans, led by then-Speaker of the House Newt Gingrich.
Republicans suffered a public backlash when voters re-elected Clinton in a landslide the following November, a lesson never forgotten by senior Republicans, including House Speaker John Boehner.
This time, Boehner tried to avoid a showdown but was overruled by his caucus, dominated since the 2010
election by newcomers endorsed by the conservative Tea Party movement.
With Boehner effectively sidelined, rank-and-file Republicans boasted of their unity. Members chanted "vote, vote, vote, vote," in their closed-door meeting, they reported later.
Afterward, Democratic Representative Louise Slaughter of New York, took to the House floor to accuse Republicans of throwing a "temper tantrum" about Obamacare under pressure from "Tea Party extremists".