Proponents fell two votes short of forcing an end to debate on the bill, which they said would diversify energy production while giving farmers an economic boost by expanding use of corn-based ethanol.

"This will not be the last vote on this bill," said Majority Leader Bill Frist, R-Tenn. "We're going to keep voting until we pass it and get it to the president."

President Bush (news - web sites) has repeatedly demanded Congress finish work on energy legislation this year.

But the bill crafted largely behind closed doors in negotiations between Senate and House Republicans failed to gain momentum in the Senate, even after it breezed through the House earlier in the week by a 246-180 vote.

Opponents threatened a filibuster, and Republican leaders needed 60 votes under the Senate's rules to close off debate and pass the bill. They fell short by just two votes. The official tally was 57-40 because Frist voted against stopping debate for technical reasons, allowing him to bring the bill up again in the future under Senate rules.

Their failure to advance the bill stunned GOP supporters of the legislation.

Sen. Pete Domenici, R-N.M., said he would explore "ways to make some changes" in the bill to get a few more votes. But he acknowledged the task would be difficult and would mean reopening negotiations with the House.

House Republicans need to understand "we just can't wave a wand and pass it. They will have to work with us," said Domenici, the bill's floor leader.

Rep. Billy Tauzin, R-La., chairman of the House Energy and Commerce Committee, said he wasn't surprised by the vote and foresaw a win after more negotiating. "I think we're still in the ballpark," he said in an interview, adding it was a matter of finding the right balance to attract a few more senators.

Opponents waged a frantic campaign for votes to derail the legislation, arguing the $31 billion bill was too expensive and amounted to a collection of subsidies to special interests.

Six Republicans joined Democrats in opposing the bill. Thirteen Democrats joined Republicans in support of the legislation.

Democratic leader Tom Daschle of South Dakota, who voted for ending debate, called the defeat "unfortunate." He said Senate energy negotiators "were undercut by manipulation by the House Republican leadership" that pressed for measures in the bill that many senators could not accept.

Approval of an energy bill has been a top priority for President Bush, who repeatedly called on Congress to finish the legislation this year.

As opponents to the bill appeared to gain strength, Vice President Dick Cheney (news - web sites) began calling GOP senators urging them not to abandon the president on the issue. Energy Secretary Spencer Abraham (news - web sites), a former senator from Michigan, was dispatched to Capitol Hill in the hours before the voting.

Republican supporters of the bill called it balanced and said it would provide for diversifying the nation's energy sources.

But a growing number of senators — both Democrats and at least six Republicans — criticized the bill as too costly, a give away to energy industries, and bad for the environment.

A particular target was a provision that would shield manufacturers of the gasoline additive MTBE from product liability lawsuits. The issue was key in getting five GOP senators from New England, where MTBE contamination of water supplies has been a major concern, to oppose the legislation.

The bill has "glaring examples of industry favors," said Sen. John McCain, R-Ariz., another opponent. He called it a "Thanksgiving turkey" stuffed with goodies for special interests.

Sen. Judd Gregg, R-N.H., also objected to the bill's price tag — an estimated $31 billion over 10 years — arguing that the measure exceeds the congressional budget ceiling.

The debate is over "allowing this country to get back into the business of producing energy," countered Sen. Larry Craig, R-Idaho. But that argument didn't sway enough senators to approve the first overhaul of the nation's energy agenda in more than a decade.

Sen. Charles Schumer, D-N.Y., said there were some good things in the bill, but he strongly opposed provisions to mandate use of corn-based ethanol in gasoline nationwide and the bill's handling of MTBE.

Democrats also objected to the way the bill had been crafted — largely behind closed doors in negotiations among Senate and House Republicans.

"It really doesn't help the Senate to prolong the inevitable. The inevitable is this bill is history. It's not going to go any place," said Sen. Harry Reid, the Senate Democratic whip.

The ethanol issue was viewed as critical for the bill to pass. The bill would double the use of ethanol, an economic boon to farm states.

But while farm-state Democrats joined Republicans in support of the measure, senators from the far West and Northeast, who were opposed to the ethanol requirements, added to the strength of the opposition.

The bill's provisions include breaks of $13 billion for oil, gas and coal industries, and $5.5 billion for renewable energy sources — wind, solar and biomass.