After months of battling with the Bush administration, California may be close to getting permission from the federal government to set its own standards for tailpipe emissions from cars and trucks.

President-elect Barack Obama is expected to grant the state a waiver to impose the tough new standards after he takes office in January, reversing a decision by the Bush administration that infuriated environmentalists.

"Obama has said very clearly he would permit California to move forward and enforce its greenhouse gas standards for cars, so we expect that the Bush administration's policies will be reversed in short order," said Frank O'Donnell, executive director of the environmental group Clean Air Watch.

Sen. Barbara Boxer, who chairs the Senate Environment and Public Works Committee, also predicted that Obama would approve the waiver.

"My expectation is it will be done because he said (during the campaign) he would do it, and I believe he will do it," said Boxer, D-Cailf.

If Obama approves the waiver, the implications will reach far beyond California.

Eighteen other states already have adopted or are in the process of adopting California's standards. The waiver would clear the way for them to impose the tougher standards as well and would force auto manufacturers to produce more fuel-efficient vehicles nationwide.

California's rules, which the state Legislature passed in 2002, would force automakers to reduce greenhouse gas emissions by 30 percent in new cars and light trucks by 2016. The state can't impose the standards, however, without a waiver from the U.S. Environmental Protection Agency.

EPA Administrator Stephen Johnson announced last December that he had decided against issuing the waiver because California did not have "compelling and extraordinary conditions" to set its own standards.

But internal documents obtained by Boxer's committee indicated the EPA staff had concluded that California did, in fact, meet the legal conditions for imposing the new rules and that the EPA was likely to lose if the issue should end up in court.

In January, California and 15 other states sued the EPA over Johnson's decision.

During the presidential campaign, both Obama and Republican John McCain pledged to approve the waiver if they were elected.

It's not clear how quickly Obama would be able to act. The new administration would have to re-evaluate the state's application and then issue a formal finding that it meets all of the necessary legal requirements, said Stanley Young, spokesman for the California Air Resources Board.

The automotive industry would likely sue to block the regulations, "but we feel that the case could be made strongly that California should be granted the waiver," Young said.

Regardless of how long it takes, Obama could signal at the start of his administration that he intends to grant the waiver, "and I would hope that would happen," O'Donnell said.

"I think that would be a very strong signal that he is committed not only to doing something positive on climate change, but making sure that states like California retain their ability to do the same," O'Donnell said.

In another move that many view as a positive sign for California, Mary Nichols, chairwoman of the state Air Resources Board, is believed to be on Obama's short list of possible candidates to head the federal EPA.

Nichols, who served as an assistant EPA administrator in the Clinton administration, "would make a superb EPA administrator," O'Donnell said.

"She understands exactly what is required in that job," he said. "She was in the middle of the biggest political fights of the Clinton era when it came to the EPA. So she understands very well how that agency runs, what its relationship is to the White House, how other cabinet departments may act."

Nichols said in a statement that she would be honored to be considered for a position in the Obama administration.