WASHINGTON — Democrats from automobile-making states and Republicans wary of government regulation blocked a Senate proposal Tuesday to toughen fuel-mileage standards for motor vehicles, virtually ensuring the provision will be left out of any new energy bill.
The 65-32 vote against the higher requirements culminated a fierce lobbying effort that pitted environmentalists against car manufacturers and the auto workers union.
Environmentalists have called tougher fuel-economy rules the most important step Congress could take to reduce U.S. dependence on foreign oil and emissions of carbon dioxide, a gas linked to global warming.
"How can you have a serious energy bill and not ... address the fuel efficiency of vehicles?" asked Sen. Richard Durbin (D-Ill.).
But with the House rejecting a similar measure earlier this year, environmentalists held little hope that the energy legislation would include the stiffer mileage standards.
Auto makers and auto union leaders contended that the proposal would hurt their industry's competitiveness -- resulting in job losses -- and lead to lighter, less safe vehicles.
"This is not the place, on the Senate floor, to make a complex decision that should involve a whole host of factors," said Sen. Carl Levin (D-Mich.).
The measure would have required cars and sport-utility vehicles to meet a 40-miles-per-gallon standard by 2015.
Currently, cars must meet an average fuel economy standard of 27.5 mpg -- unchanged for more than a decade. The standards for light trucks, including SUVs, minivans and pickups, is 20.7 mpg. That is due to rise to 22.2 mpg for the 2007 model year.
Rather than stiffen the requirements, the Senate approved an industry-backed amendment to direct the Department of Transportation to set fuel-economy standards on factors that include how tougher rules would affect vehicle safety and auto industry jobs.
Environmentalists contend that the measure, which passed 66-30, could set up new obstacles to raising the standards.
The vote came as President Bush and Vice President Dick Cheney met with a bipartisan group of lawmakers at the White House to press them to finish work on an energy bill. Bush has called such a measure vital to economic growth and national security.
The House version of the bill, passed in April, includes a Bush-backed provision to open Alaska's Arctic National Wildlife Refuge to oil drilling. But that measure has been thwarted in the Senate and, like the tougher fuel-efficiency standards, is not expected to be part of a final bill.
Both the Senate and House bills contain other measures to promote domestic energy production, as well as proposals to spur conservation. These include promoting construction of a pipeline to bring natural gas from Alaska to the lower 48 states, expanding nuclear power and doubling the amount of ethanol that must be added to the nation's gasoline supply.
The Senate could vote on its bill this week.
Tuesday's debate on the higher mileage requirements illustrated that the complex politics of the energy debate can produce strange -- and temporary -- bedfellows. Eighteen Democrats, many of them usually on the opposite side of Republicans on environmental issues, joined virtually all the Senate's GOP members in opposing the tougher standards.
Among the Democrats voting against the measure were Mary Landrieu and John B. Breaux of Louisiana, Levin and Debbie Stabenow of Michigan, Joseph R. Biden Jr. of Delaware, Evan Bayh of Indiana, Zell Miller of Georgia and Barbara A. Mikulski of Maryland. All come from states with vehicle-manufacturing plants.
California Democratic Sens. Dianne Feinstein and Barbara Boxer joined 25 other Democrats, four Republicans and one independent voting for the tougher standards.
Supporters of the measure noted that because of the increasing popularity of SUVs, overall fuel economy has declined since the 1980s.
But opponents contended that Americans could be deprived of their vehicles of choice.
"I don't want to tell parents ... they cannot get the SUV or minivan they wanted for their family or business because Congress decided it would be a bad choice," said Sen. Christopher S. Bond (R-Mo.).
Sens. John F. Kerry of Massachusetts and Joe Lieberman of Connecticut -- both Democratic presidential candidates -- have made tougher fuel standards a centerpiece of their proposals to cut U.S. dependence on foreign oil.
But both were absent Tuesday, as was another Democratic presidential contender, Sen. Bob Graham of Florida. Sen. John Edwards (D-N.C.), who is also running for president, voted for the tougher standards.
Bush opposes efforts to legislate what the White House has termed "an arbitrary increase" in fuel standards. He instead advocates tax incentives to encourage consumers to buy gas-electric hybrid vehicles. He also has proposed spending more than $1 billion to speed up the development of cars that run on pollution-free hydrogen fuel cells.