Detroit ? Worried about their jobs and warned that failure could lead to a depression, hundreds of leaders of the United Auto Workers voted overwhelmingly Wednesday to make concessions to the struggling Detroit Three, including all but ending a much-derided program that let laid-off workers collect up to 95 percent of their salaries.

“Everybody has to give a little bit,” said Rich Bennett, an official for Local 122 in Twinsburg, Ohio, which represents Chrysler workers. “We’ve made concessions. We really feel we’re doing our part.”

Union leaders also agreed to let the cash-starved automakers delay billions of dollars in payments to a union-administered trust set to take over health care for blue-collar retirees starting in 2010.

In addition, they decided to let the Detroit leadership begin renegotiating elements of landmark contracts signed with the automakers last year, a move that could lead to wage concessions.

The vote came on the eve of congressional hearings on as much as $34 billion in loans that General Motors and Chrysler say are critical to their survival. Ford has said it may be able to hang on through 2009 without additional credit.

Democratic congressional leaders say they want to act to prevent one or more of the automakers from collapsing, but they have made no commitments to approve an unpopular bailout at a time of economic peril.

Senate Majority Leader Harry Reid said a Democratic plan to tap the Wall Street rescue fund to save U.S. automakers does not have the votes to pass.

The Bush administration has suggested that aid to the automakers come from a

$25 billion loan already approved by Congress for fuel-efficient vehicles.

UAW President Ron Gettelfinger said the union must help persuade Congress to offer new loans or risk destroying what he said is the country’s economic spine.

“Let’s look at the backbone and the millions of jobs lost if we lost this industry,” he said.

Earlier in the day, Chrysler Vice Chairman Jim Press went a step further, warning of a depression if even one automaker runs out of cash.

“We’re on the brink with the U.S. auto manufacturing industry,” Press told The Associated Press in an interview. “If we have a catastrophic failure of one of these car companies, in this tender environment for the economy, it’s a huge blow. It could trigger a depression.”

Both Chrysler LLC and General Motors Corp. are so perilously low on cash that the companies may not be able to pay all their bills by the end of the year.

GM wants a total of $18 billion in loans. Chrysler is seeking $7 billion, and both manufacturers say they need cash this month.

Ford Motor Co., which borrowed billions before credit markets tightened, says it can survive through 2009 and may not need to tap the $9 billion credit line it requested.

As a further sign of the companies’ dire straits, Moody’s Investors Service on Wednesday downgraded its ratings for GM and Chrysler, sending them further into noninvestment, or “junk,” status.

Sent home empty-handed last month, executives from all three companies knocked on doors on Capitol Hill and made television appearances Wednesday, hoping the detailed plans they submitted Tuesday would convince hostile lawmakers to help.

CEOs from all three, plus Gettelfinger, will appear before Senate and House committees today and Friday.