WASHINGTON - Humbled and increasingly desperate as car sales plummet, the heads of Detroit's Big Three automakers said yesterday that they were willing to accept government oversight of their spending in return for $34 billion in government loans to keep them afloat.

The chief executives said they would be willing to take the money in stages, which would allow the government to put the brakes on additional funding if the companies were not making solid progress in reinventing themselves as leaner, more profitable enterprises.

But skepticism remained high on Capitol Hill, with lawmakers questioning the automakers' commitment to becoming more competitive and worrying that taxpayers' money would be quickly frittered away. As a result, General Motors Corp., Ford Motor Co. and Chrysler L.L.C. still faced tough odds in getting government help this year.

"In just two short weeks, the price tag has jumped" from $25 billion to $34 billion, said Sen. Richard Shelby (R., Ala.), the Senate Banking Committee's top Republican. "I'm interested in hearing what changed and why we should believe things will get better."

Democrats generally are more sympathetic to the automakers' plight, saying that thousands of jobs could be lost and the nation's industrial might put in jeopardy.

"None of us relishes this task that we are asked to consider, yet who among us believes we should risk the consequences of the collapse of . . . one or more domestic automobile manufacturers?" Banking Committee Chairman Christopher J. Dodd (D., Conn.) said at the start of a nearly six-hour hearing. "Make no mistake about it - those consequences would be severe and sweeping."

The executives face another grilling today when they appear before the House Financial Services committee.

The idea of paying out government funds in pieces instead of all at once appeared to gain traction among members of Congress, although nothing approaching a final deal was at hand.

As described to the auto executives who accepted it, the proposal calls for about half the money to be disbursed quickly to keep the companies afloat through March 31. The rest would be held until a government board of trustees was convinced the companies were making progress toward becoming more competitive and retooling their lineups to offer more fuel-efficient cars.

Sen. Charles Schumer (D., N.Y.) pushed the idea of a single trustee designated by the president to control disbursement of additional money after March 31 and force changes on the companies and the United Auto Workers, which has been criticized for protecting current compensation packages for its members.

A common concern among lawmakers was that the $34 billion would be just the beginning.

Mark Zandi, chief economist at Moody's Economy.com, testified to the committee that the companies would need $75 billion to $125 billion in government loans to avoid bankruptcy over the next two years.

Zandi said the economic cost of an auto-industry failure would be "cataclysmic."

GM said it needed $4 billion this month to avoid bankruptcy, an additional $8 billion to avoid it next year, and a $6 billion line of credit if economic conditions worsened. Chrysler said it needed $7 billion in loans or it could run out of cash early next year.

Ford, which is more financially stable, requested only a "stand-by line of credit" of up to $9 billion. But Ford said a failure by either competitor could threaten it as well because the automakers share many suppliers.

In their appearance before the Banking Committee, the attitude of the company executives was markedly different from November, when they first argued for a bailout.

In the earlier hearing, they were vague, evasive and mostly unwilling to agree to requests by lawmakers for concessions in exchange for emergency loans. Yesterday, the executives were so eager to please that they agreed to almost every request from committee members.

For example, in the earlier appearance before Congress, only Chrysler chief executive Robert Nardelli agreed to reduce his annual salary to $1. Now, all three have agreed.

Also, faced with sharp criticism for traveling to Washington for those hearings in separate private jets, the CEOs all drove from Michigan in advanced hybrid cars this time.

"We're sorry to be asking for this support. We wish the market conditions were better. They're not. So this is what we need to do," Wagoner said after driving up to Capitol Hill in a test version of the Chevrolet Volt electric car.

Dodd and several other senators declared themselves largely satisfied with the plans and said they were searching for a way to pass a bailout soon.

"Nothing concentrates the mind like a death sentence," Dodd said.