President Barack Obama and his top advisers have determined that neither company is viable and that taxpayers will not spend untold billions more to keep the pair of automakers open forever. In a last-ditch effort, the administration gave each company a brief deadline to try one last time to convince Washington it is worth saving

Frustrated administration officials said Chrysler cannot function as an independent company under its current plan. They have given Chrysler a 30-day window to complete a proposed partnership with Italian automaker Fiat SpA, and will offer up to $6 billion to the companies if they can negotiate a deal before time runs out.

If a Chrysler-Fiat union cannot be completed, Washington plans to walk away, leave Chrysler destined for a complete sell-off. No other money is available.

For GM, the administration offered 60 days of operating money to restructure. A frantic top-to-bottom effort began Sunday after CEO Rick Wagoner resigned under pressure from the White House.

One official said a majority of the GM board was expected to step down.

Officials said GM had not made good on promises made in exchange for $13.4 billion in government loans, although there are no plans to call in those loans.

An exasperated administration official noted that the companies had not done enough to reduce debt; in some cases, it actually increased during this restructuring and review process.

Aides note that Obama inherited the auto mess from his predecessor, President George W. Bush.