General Motors Corp., Ford Motor Co. and Chrysler LLC, the three biggest U.S. automakers, may be forced into bankruptcy as the global credit freeze damps U.S. sales, Standard & Poor's analyst Robert Schulz said.

"Macro factors could overwhelm them at some point" even as GM, Ford and Chrysler vow to stick with their turnaround plans, Mr. Schulz, S&P's lead automotive credit analyst, said yesterday. The companies said they have no plans to seek bankruptcy protection.

His assessment underscored the pressure on the industry as the worsening credit crisis makes it harder for buyers to get loans and dealers to finance their operations. S&P said yesterday that it might further trim credit ratings for GM and Ford on forecasts for 2009 auto demand to fall to its lowest since 1992.

With all three companies working to boost cash, any bankruptcy filing would be a last resort, not a "strategic" decision, Mr. Schulz said.

"Bankruptcy is not an option GM is considering," spokeswoman Renee Rashid-Merem said yesterday, reiterating comments of earlier in the week. "It's not in the interests of our employees, stockholders, suppliers or customers."

Still GM is likely to announce further production cuts and possible plant closures as early as next week as it deals with slumping sales and a collapse in its stock price, a person with knowledge of the company's plans said yesterday.

The person, who did not want to be identified because the plans are not finalized, said the cuts likely will hit engine, transmission and stamping operations to correspond with a June announcement that GM would close four truck and sport utility vehicle assembly plants.

The closure dates for those plants likely will be accelerated, the person said. GM announced last week that its Moraine, Ohio, SUV factory will close Dec. 23, and it has said it will idle assembly factories in Oshawa, Ontario; Toluca, Mexico; and Janesville, Wis., by 2010.

Chairman and CEO Rick Wagoner said last month that GM would have to make adjustments, particularly in stamping factories.