Turning to Washington for a lifeline, General Motors Corp. has asked lawmakers for up to $18 billion to stave off collapse, promising in return to slash executive pay and jettison its poorly performing brands.

GM, along with Ford Motor Co. and Chrysler, submitted its restructuring plan to Congress on Tuesday, the same day domestic and foreign automakers reported a withering 37% U.S. sales decline.

The depths of GM's troubles were brought fully to light in its proposal, released late Tuesday. In November, GM said it could run out of operating cash sometime in the first six months of 2009. Now it appears that GM could fail in a matter of weeks without immediate aid.

"There is no Plan B," said Fritz Henderson, GM's president and chief operating officer, who faces a 30% pay cut himself. "Frankly, the shortage of liquidity does focus the mind."

Together, the Big Three U.S. automakers are asking Congress for $34 billion in low-cost government loans -- $9 billion more than the roughly $25 billion the automakers had sought just last month.

GM said it would need $4 billion immediately to avoid complete collapse before year's end, plus $8 billion early next year. On top of that, the company wants access to a $6-billion line of credit. Last month it had requested $10 billion to $12 billion.

"Absent support, the company can't fund its operations," Henderson said.

For its part, the automaker said it would eliminate or sell its Saab and Saturn brands, shrink its venerable Pontiac division to a few niche models, lay off tens of thousands of employees and put nearly 2,000 dealers out of business.

GM also said it would reduce pay 20% or more for four top executives and pay Chairman and Chief Executive Rick Wagoner a $1 annual salary.

Chrysler again requested $7 billion in a bridge loan to help it operate through 2009. Ford, which last month sought $7 billion to $8 billion, asked for a $9-billion line of credit but took pains to point out that it might not need the money.

The three Detroit automakers prepared their plans at the behest of Congress, which sent the companies' top executives home last month after excoriating them for failing to make a compelling case for taxpayer support.

This week the executives will return to Washington -- driving, this time, instead of taking private jets. They are set to appear before the Senate Banking Committee on Thursday and the House Financial Services Committee on Friday. A vote on a bailout could come next week.

House Speaker Nancy Pelosi (D-San Francisco) said the plans would be reviewed by congressional committees, the Federal Reserve, the Government Accountability Office and Bush administration officials.

"We want to see a commitment to the future. We want to see a restructuring of the approach that they have -- a new business model," she told reporters Tuesday.

At the same time, Pelosi said, the government had little choice but to help one of the nation's most important industries. "Everybody is disadvantaged by bankruptcy, including our economy, so that's not an option," she said.

Both Chrysler and GM have repeatedly dismissed the idea of filing for bankruptcy protection and continued to do so Tuesday. Still, GM's plan indicates that at current spending levels, it would run out of cash sometime this month.

The latest bleak window into Detroit's troubles came on the same day that the industry as a whole reported the worst U.S. sales month since January 1982, according to Autodata Corp.

GM, in reporting its own 41% sales decline from a year earlier, painted the results with an even darker brush. According to GM's chief sales analyst, Mike DiGiovanni, the month's sales, adjusted to reflect population growth, were the worst since 1958.

The new dealer data, combined with Monday's official certification that the U.S. has been in recession since last December, "will embolden Congress to act quickly," predicted Thomas Mann, a senior fellow at the Brookings Institution.