The US government has begun a partial shutdown after the two houses of Congress failed to agree a new budget.
The Republican-led House of Representatives insisted on delaying President Barack Obama’s healthcare reform – dubbed Obamacare – as a condition for passing a bill.
More than 800,000 federal employees face unpaid leave with no guarantee of back pay once the deadlock is over.
It is the first shutdown in 17 years and the dollar fell early on Tuesday.
Goldman Sachs estimates a three-week shutdown could shave as much as 0.9% from US GDP this quarter.The White House’s budget office began notifying federal agencies to begin an “orderly shutdown” as the midnight deadline approached.
Shortly after midnight, President Obama tweeted: “They actually did it. A group of Republicans in the House just forced a government shutdown over Obamacare instead of passing a real budget.”
House Speaker John Boehner told reporters he hoped the Senate would agree to a bipartisan committee known as a conference “so we can resolve this for the American people”.
“The House has voted to keep the government open but we also want basic fairness for all Americans under Obamacare,” he said.
The Senate is to meet again at 09:30 (13:30 GMT) on Tuesday.
The BBC’s Mark Mardell in Washington says the divide in US politics has grown so bitter that government itself cannot function.
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State department will be able to operate for limited time
Department of defence will continue military operations
Department of education will still distribute $22bn (£13.6bn) to public schools, but staffing is expected to be severely hit
Department of energy – 12,700 staff expected to be sent home, with 1,113 remaining to oversee nuclear arsenal
Department of health and human services expected to send home more than half of staff
The Federal Reserve, dept of homeland security, and justice dept will see little or no disruption
US Postal Services continue as normal
Smithsonian institutions, museums, zoos and many national parks will close
US shutdown in 60 seconds
Who will be affected
Q&A: 2013 US budget brawl
Democrats were never likely to make concessions on healthcare reform – Mr Obama’s signature achievement and a central issue in last year’s presidential election, our correspondent says.But Republicans have made demands that they knew would not be met rather than be accused of weakness and betrayal by their own hardliners, he adds.
On Monday afternoon, the Democratic-led Senate voted 54-46 against a bill from House Republicans that would have funded the government only if President Obama’s healthcare law was delayed for a year.
Major portions of the healthcare law, which passed in 2010 and has been validated by the US Supreme Court, are due to take effect on Tuesday regardless of whether there is a shutdown.
President Obama went on national television to criticise Republicans for trying to refight the last election.
Engineers with the US Navy talk to the BBC about what they will do during a shutdown: Make skis
A shutdown would have “a very real economic impact on real people, right away,” he said, adding it would “throw a wrench” into the US recovery.
“The idea of putting the American people’s hard-earned progress at risk is the height of irresponsibility, and it doesn’t have to happen.”After the Senate vote, the chamber’s Democratic majority leader blamed Republicans for the imminent halt to all non-essential government operations.
“It will be a Republican government shutdown, pure and simple,” said Harry Reid, referring to the Republicans as “bullies”.
Mr Obama has signed legislation ensuring that military personnel would be paid. The defence department had advised employees that uniformed members of the military would continue on normal duty, but that large numbers of civilian workers would be told to stay home.
Under the shutdown, national parks and Washington’s Smithsonian museums will close, pension and veterans’ benefit cheques will be delayed, and visa and passport applications will go unprocessed.
John Boehner: “I hope the Senate accept our offer”
Programmes deemed essential, such as air traffic control and food inspections, will continue.
The US government has not undergone a shutdown since 1995-96, when services were suspended for a record 21 days.
Republicans demanded then-President Bill Clinton agree to their version of a balanced budget.
As lawmakers grappled with the latest shutdown, the 17 October deadline for extending the government’s borrowing limit looms even larger.
Democrat Jim McGovern to Republicans: “You own this”
On that date, the US government will reach the limit at which it can borrow money to pay its bills, the so-called debt ceiling.
House Republicans have also demanded a series of policy concessions – including on the president’s health law and on financial and environmental regulations – in exchange for raising the debt ceiling.
“I’m thoroughly disgusted with our politicians,” Ken Griffith from Kentucky told the Associated Press news agency.
“They’re acting like a bunch of three year old children. It’s who can hold their breath the longest.”