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Also on Monday, Mr. Obama asked his administration to write rules that would require auto manufacturers’ fleets to meet stricter standards by 2011 and put cars on track to meet a 2007 law that sets a target of 35 miles per gallon by model year 2020 - about 10 miles per gallon higher than the current standard.

The president said he does not want to sink the auto industry, but that he wanted to push it to adapt to a greener economy and build cars consumers want.

“Our goal is not to further burden an already struggling industry. It is to help America’s automakers prepare for the future,” he said.

By backing California’s rules, Mr. Obama also has put pressure on Congress to act on a national standard or face the prospect of a patchwork across jurisdictions, including Maryland and the District, that have followed California’s lead.

Michigan lawmakers on Monday pleaded for a national standard.

“As the administration begins its work to reduce greenhouse-gas emissions, I urge the president and his Environmental Protection Agency to develop a strong, national standard for vehicle emissions, rather than a patchwork of state standards,” said Gov. Jennifer M. Granholm, a Democrat.

The Natural Resources Defense Council said documents that Ford Motor Co. and General Motors Corp. submitted to Congress last year show they can meet the fuel-efficiency standards.

“Detroit consistently underestimates their capacities,” said David Doniger, policy director of NRDC’s climate center. “They consistently demonstrate they can do more than they previously said.”

Mr. Doniger said Mr. Obama is creating good competition by asking states to lead, but also by pushing his own administration to impose strict standards.

“This is a great start in making real the president’s campaign vision of really changing America’s energy and global-warming policies,” he said.

• Christina Bellantoni and Tom LoBianco contributed to this report.