US House Speaker Nancy Pelosi has thrown her support behind the premise that General Motors Corp, the largest US automaker, is too big to be allowed to fail.

In urging Congress to enact emergency aid for the ailing auto industry, Pelosi rejected calls to let GM collapse and sided with the company and its allies in trying to prevent a "devastating" domino effect that would cost millions of jobs.

"Trying to reorganize the auto industry in bankruptcy would be as close to reorganizing the whole US economy as you could get," said Alan Gover, a bankruptcy lawyer with White & Case LLP in New York.