US shutdown looms amid political rifts over health law
The US government has less than 48 hours to avert a shutdown of government services amid political divisions over President Obama's healthcare law.
On Sunday, the Republican-run House of Representatives voted to pull the law's funding, raising chances of a shutdown.
The government needs to agree a new policy-wide spending bill before the US fiscal year ends at midnight on Monday.
If it fails, non-essential federal services face closure, with employees sidelined or left working without pay.
Early on Sunday, the House passed an amended version of the Senate spending bill that removed funding from the healthcare law.
US Senate Majority leader Harry Reid has vowed that his Democrat-led chamber will reject the Republican bill.
But with the Senate not due to meet again until Monday afternoon, it will have just hours to pass a stand-alone bill free of any measures that undermine the law.
In a statement, Senator 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.
Speaking for the president, White House spokesman Jay Carney said: "Any member of the Republican Party who votes for this bill is voting for a shutdown." The president, he said, would also veto the Republican bill.
However, House Republicans went ahead with the changes, ignoring the veto threat and passing the bill in a late-night session by 231 votes to 192.
The Senate is controlled by Mr Obama's Democratic party, while the Republicans hold the majority in the House of Representatives.
"House and Senate like two locomotives barreling toward one another ... in slow motion," tweeted Republican Representative Scott Rigell.
The looming shutdown, which would be the first for 17 years, is one of two fiscal crises facing the US government.
On 17 October, the US treasury department's authority to borrow money to fund its debt obligations expires unless Congress approves a rise in the so-called debt ceiling.
On Friday, President Obama urged House Republicans to pass the Senate's stopgap budget bill and to extend the debt limit, and demanded they not threaten to "burn the house down because you haven't gotten 100% of your way".
Mr Obama said if the nation were to default on its debt, it would have a "profound destabilising effect" on the world economy.
"Voting for the treasury to pay its bills is not a concession to me," he said. "No-one gets to hurt our economy... just because there are a couple of laws [they] don't like."
He described the healthcare law as "a done deal" and said the Republican-backed repeal effort was "not going to happen".
Mr Obama said the Senate had "acted responsibly" in passing the budget measure and that now it was up to Republicans in the House of Representatives "to do the same".
If the government does shut down on 1 October, as many as a third of its 2.1 million employees are expected to stop work - with no guarantee of back pay once the deadlock is resolved.
National parks and Washington's Smithsonian museums would close, pension and veterans' benefit cheques would be delayed, and visa and passport applications would be stymied.
Programmes deemed essential, such as air traffic control and food inspections, would continue.
The defence department has advised employees that uniformed members of the military will continue on "normal duty status", but "large numbers" of civilian workers will be told to stay home.