Just a few months ago, momentum appeared to be building for cars fueled by compressed natural gas as a way to replace foreign oil imports.

T. Boone Pickens, the former oil magnate with a big stake in natural gas distribution, and Aubrey McClendon, chief executive of Chesapeake Energy, a natural gas producer, poured tens of millions of dollars into television commercials promoting the idea, and a number of bills were introduced in Congress offering tax incentives to automakers and consumers to switch to natural gas vehicles.

None of those bills have gone very far and the natural gas boom on the airwaves has gone quiet.

Meanwhile, natural gas was dealt a major blow in California with the defeat of Proposition 10. That ballot initiative, which would have created $5 billion in general obligation bonds to promote purchases of compressed natural gas and other alternative-fuel vehicles, went down in a landslide at the polls — despite heavy financial backing from Mr. Pickens.

But new hope for natural gas fuel interests may be on the way: When President-elect Barack Obama chose Representative Rahm Emanuel of Illinois to be his chief of staff, he chose one of Congress’s biggest proponents of compressed natural gas cars.

Last summer Mr. Emanuel introduced legislation (PDF) that would mandate automakers to build 10 percent of their fleet with natural gas fueled vehicles by 2018. His bill also included tax credits and other incentives and mandates to spread natural gas pumps to filling stations across the country.

The bill has gone nowhere, but natural gas stalwarts have expressed optimism upon Mr. Emanuel’s selection. Tom Price, a Chesapeake vice president, was quoted by The Associated Press as saying it “could be quite advantageous” having Mr. Emanuel at the president’s side as one of his closest advisers.

And with the auto industry looking for help urgently, Mr. Emanuel is going to have a chance to press his case.