After hours of tense late-night bargaining, senators failed to reach a deal on a $14 billion emergency loan package for U.S. automakers backed by the White House and congressional Democrats, scuttling the rescue for the week and possibly for the year.

“We have not been able to get this over the finish line,” Senate Majority Leader Harry Reid , D-Nev., said. “I dread looking at Wall Street tomorrow. It’s not going to be a pleasant sight.”

The brinksmanship came after Democrats and Republicans failed to reach agreement on the timing of union concessions and the Senate failed to invoke cloture on a “shell” bill that would be used as a vehicle for the bailout.

Reid moved up the cloture vote rather than go through a series of procedural votes all weekend that would yield no success, he said. Both he and Senate Minority Leader Mitch McConnell , R-Ky., left it unclear when they would revisit the issue.

After the Senate failed to muster 60 votes needed to proceed to the bill, on a 52-35 vote, Reid said there would likely be no more Senate work this year and called on President Bush to use his authority under the $700 billion financial industry bailout bill to help automakers.

Democrats and Republicans traded blame for the blowup, with the GOP laying it on the United Auto Workers’ (UAW) reluctance to accept tough concessions within a matter of months and Democrats countering that Republicans were unfairly demanding stronger givebacks from workers than from Wall Street executives who have gotten federal bailouts.

“If they want a bill, they can get one and it would be a good one to save these companies,” said Alabama Republican Richard C. Shelby . “But we’re not quite there yet. It all has to do with labor.”

Debbie Stabenow , D-Mich., countered: “The only thing that matters to the majority of those on the other side of the aisle is that somehow workers get paid too much in this country and unless we sock it to the worker, they will not be willing to allow a $14 billion bridge loan to be able to save an industry.”

After Republicans signaled that they would reject a House-passed bill, Bob Corker , R-Tenn., spent hours in negotiations with Banking Chairman Christopher J. Dodd , D-Conn., late Thursday, holding out hope of a late-night vote on a plan that would slash debt and labor costs.

When Corker presented the tentative plan to his Republican colleagues at about 9 p.m. in the Lyndon B. Johnson room next to the Senate chamber, conservatives balked.

The final sticking point was the UAW’s desire to have until 2011 to reduce pay and benefits to levels paid by Japanese automakers with U.S. plants. Republicans want it done by March 31.

“The sticking point that we are left with is the question of whether the UAW is willing to agree to a parity pay structure with other manufacturers in this country by a date certain. And I understand their reluctance to do that,” McConnell said.

The collapse of the talks came suddenly and after a surge of optimism among senators earlier in the evening that a deal was within reach.

He complained that a car czar who would administer the loan program would have “nearly unlimited power to allocate taxpayer dollars but limited ability to force the kinds of tough concessions that long-term viability would require.”

Corker’s plan would require considerable concessions from creditors. GM, for instance, had $62 billion in debt, according to a restructuring plan it submitted to Congress this month.

Corker said he had been in discussion with executives from GM and Cerberus Capital Management LP — Chrysler’s majority owner — and the companies were receptive to the plan.

“If we just take a moment, we can actually do something that is great for the economy,” he said, adding that if nothing is done, the industry’s chances of long-term survival would be imperiled.

Corker also said he thought his colleagues across the aisle might be willing to work with his plan.

“I think there is an openness,” he said. “I think there is potential real momentum right now, so we’ll see.”

But Sen. Carl Levin , D-Mich., a key auto industry ally, said that the Corker plan puts too many specific conditions on the automakers, and he urged Bush to lobby Senate Republicans to support the House-passed bill.

It was also uncertain how House Democrats would react to a modified plan, especially after giving ground to the Bush administration on several key issues, including funding the loans through an Energy Department program designed to boost fuel efficiency. However, after the House acted, Speaker Nancy Pelosi , D-Calif., left the door open to considering a different Senate plan.

The Bush administration signaled early in the day that it was open to changes in the deal it had negotiated with Democrats.

“We think that there are members of Congress who might have some ideas on how things could possibly be improved in the bill. We’re willing to listen to them,” said White House Press Secretary Dana Perino.

Noting that unemployment claims are at their highest level in 26 years, she said, “We believe that the economy is in such a weakened state right now that adding another possible loss of 1 million jobs is just something our economy cannot sustain at the moment.”

Catharine Richert, Benton Ives and Kathleen Hunter contributed to this story.