By MICHELINE MAYNARD


DETROIT - President-elect Barack Obama leveled a stern warning at General Motors and Chrysler last month after the federal government promised them billions to help them survive:“The auto companies must not squander this chance to reform bad management practices.”

Once he takes office, the bailout will give him a tool to prod the industry to change, but it will also test his resolve as he pushes it in new directions.

Mr.Obama, after all, has been thinking out loud about the future of the American automobile industry for years, well before his presidential campaign began. He co-sponsored two bills in 2006, during his second year as a United States senator - one to raise fuel economy standards, and the other to encourage the use of alternative fuels.

His writings and speeches on the auto industry suggest a keen interest in finding ways, including new technology, to improve the fuel efficiency of the cars and trucks that Americans drive.

But with Detroit in a fragile financial state, it is unclear how many compromises he will have to make in pursuing his agenda for the auto industry.

By all accounts, Mr.Obama’s personal interest in the industry stems from his interest in environmental issues. In a speech to the Economic Club of Detroit in May 2007, Mr.Obama said the Big Three auto companies had done little to lessen the nation’s dependence on foreign oil and needed to improve their vehicles’fuel efficiency.

“The auto industry’s refusal to act for so long has left it mired in a predicament for which there is no easy way out,”Mr.Obama said.

He added,“For years, while foreign competitors were investing in more fuel-efficient technology for their vehicles, American automakers were spending their time investing in bigger, faster cars. And whenever an attempt was made to raise our fuel efficiency standards, the auto companies would lobby furiously against it.”

Environmentalists say the speech in Detroit was a sign of commitment to prodding the auto companies to build more fuel-efficient vehicles.

“I think he gets it,”said Daniel Becker, director of the Safe Climate Campaign for the Center for Auto Safety, a Washington consumer advocacy group.

Mr.Obama, who received standing ovations at the beginning and conclusion of his speech, said he wanted to be blunt with the Detroit companies on their home turf.

“I’m making this proposal here today because I don’t believe in making proposals in California and giving a different speech in Michigan,”he said.

A year earlier, in his 2006 book,“The Audacity of Hope,”Mr.Obama wrote that“fuel-efficient cars and alternative fuels like E85, a fuel formulated with 85% ethanol, represent the future of the auto industry. It is a future American car companies can attain if we start making some tough choices now.”

With Detroit in crisis, there is little room for hesitation after Mr.Obama reaches office.