The struggling US carmaker Chrysler is to halt production at all 30 of its plants for one month.
President Bush will not allow a "disorderly collapse" of the US car industry, the White House has said.
Chrysler needs to save money as it waits for the US government to find a way to help the car industry.
Spokeswoman Dana Perino said the President was nearing a conclusion on how to provide the carmakers with financial assistance.
A $14bn (£9.4bn) bail-out deal for the industry failed in the Senate last week, raising fears of job cuts and a possible industry collapse.
She said a disorderly collapse of the Big Three was "not an option", though she ruled out any bail-out on Thursday.
Chrysler also needs to reduce production to reflect falling demand as the economy stumbles.
A $14bn (£9.4bn) rescue failed in the Senate last week, raising fears of job cuts and a possible industry collapse.
Dealers have been unable to sell cars even to people with the confidence to buy them, because they have been unable to take out car-loans.
In a statement to reporters, Ms Perino said: "We're nearing a conclusion, we're narrowing options, I just don't have anything for you today."
"As a result of the financial crisis, the automotive market remains depressed due to the continued lack of consumer credit for potential buyers," Chrysler said in a statement.
The Big Three US carmakers are waiting for the US government to find a way to help the struggling car industry.
Job losses
Factory shutdowns
It left open the possibility that the plants would be closed for more than a month.
All car firms have announced production cuts as the economic slowdown has slashed car sales.
"Impacted employees will not return to work any sooner than Monday 19 January," it said.
Chrysler is to halt production at all 30 of its factories for one month.
In announcing its plant closures, Chrysler also left open the possibility that the factories would be closed for more than a month.
Employees would not return to work any sooner than Monday 19 January, it said.
GM has suspended major work on its $370m engine factory in Michigan, where it plans to build a new small car engine which is key to its efforts to reinvent itself as a maker of fuel-efficient and all-electric cars.
The new plant is scheduled to build a turbocharged 1.4-litre engine for the Chevrolet Cruze small car and another version of the engine to provide backup power to its electric car, the Chevrolet Volt.GM is suspending work on an engine plant for its Volt electric car
Last week, GM said it was shutting down 30% of its North American production.
Also on Wednesday, Ford announced it was to extend the normal two-week Christmas shut-down at 10 of its North American plants for an extra week.
Also on Wednesday, Ford announced it was to extend the normal two-week Christmas shut-down at 10 of its North American plants for an extra week.
Last week, General Motors announced it was shutting down 30% of its North American production.
Meanwhile, GM has denied reports it had restarted merger negotiations with Chrysler - following the suspension of their talks earlier this year.
Chrysler, Ford and General Motors have warned that millions of jobs could be lost if the government does not agree to a package of loans to support the industry.
Earlier this year, both Chrysler and General Motors held talks on a possible merger.
However, GM spokesman Tony Cervone denied that talks had re-opened.
"We have had no talks with them since we announced during our third quarter earnings call that the talks had been suspended," he said.
Chrysler, Ford and GM have repeatedly warned that millions of jobs could be lost if the government does not agree to a package of loans to support the industry.
While 46,000 Chrysler employees will be directly affected by the plants closure, many more Americans whose jobs depend on the big car makers will be watching with great concern, says the BBC's North America editor, Justin Webb.
While 46,000 Chrysler employees will be directly affected by the plants closure, many more Americans whose jobs depend on the big car makers will be watching with great concern, says the BBC's North America editor, Justin Webb.
The Bush administration has said it will act to prevent a disorderly collapse of the car industry, and loans to keep the big three companies in business could be arranged within days, our correspondent adds.
The Bush administration has said it will act to prevent a disorderly collapse of the car industry, and loans to keep the big three companies in business could be arranged within days, our correspondent adds.
The White House warned on Tuesday that the carmakers would have to make "concessions" to secure the bail-out.
The White House warned on Tuesday that the carmakers would have to make "concessions" to secure the bail-out.
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