WASHINGTON – The Senate soundly defeated a proposal Wednesday for mandatory reductions in heat-trapping pollution that may be warming the Earth. Supporters managed to get five fewer votes than they did two years ago.

The proposal to cap greenhouse gases at 2000 levels within five years lost by a 60-38 vote. It was a victory for President Bush’s policies that focus on voluntary actions by industry to address the problem.

Separately, the Senate agreed to give Washington clear authority to override states’ objections to the location of liquefied natural gas terminals.

Senators rejected, by 52-45, an amendment to a broad energy bill that would have allowed governors to veto a federal permit for such a terminal because of state concerns about safety or environmental harm.

Proponents said deciding where to put these facilities was a federal matter because imports will help meet a growing demand for natural gas and perhaps lower prices. But opponents of the idea said states should have a greater say because of concerns about possible tanker spills and terrorism.

“We’re not talking about the siting of a neighborhood ballpark or a Wal-Mart,” said Sen. Olympia Snowe, R-Maine, which has rejected several LNG projects. “It’s a states’ rights issue, plain and simple.”

The debate about the climate was seen by some as a barometer of congressional support for Bush’s strategy. His approach has come under criticism from environmentalists and some European leaders who say it does not adequately address one of the most pressing environmental issues.

Snowe and Sen. Susan Collins, R-Maine, voted for the cap.

Sen. John McCain, R-Ariz., urged his colleagues to support the measure he sponsored with Sen. Joe Lieberman, D-Conn., though he realized the long odds.

“I can take the temperature” of the Senate, McCain said.

On Tuesday, senators had approved modest proposals that would require no cuts in emissions but would increase support for new clean-energy and carbon-capturing technologies.

“The evidence is now compelling, overwhelming. The world knows that climate change is real,” McCain said. “Those who have debunked this and continue to debunk it will have somebody to answer to in not too many years from now.”

The approach approved on Tuesday was “meaningless” and “a fig leaf,” he said, to hide the fact that the United States is doing little to reduce this kind of pollution. Many scientists believe it is trapping heat in the atmosphere and causing the Earth to warm.

Two years ago, the McCain-Lieberman proposal got 43 votes when it was offered as part of an energy bill.

Opponents said mandatory caps on greenhouse emissions would hurt the economy while driving the coal and other industries out of business. They also said such caps would do little to solve the climate problem because emissions are continuing to grow in China and elsewhere.

“The reason this bill can’t pass is because it can’t be implemented,” said Sen. Pete Domenici, R-N.M.

He said Bush is pressing for voluntary measures to rein in the growth in emissions “and I don’t argue with him.”

Sen. James Inhofe, R-Okla., one of the leading skeptics of climate change science, said, “Energy prices and the economy is what we’re talking about.” He said the mandatory caps would be “devastating” to industry because of their cost.

When it came to imports of liquefied natural gas, many senators from coastal states objected to a part of the energy bill that says federal regulators have “exclusive” authority in the final say about where a facility is built.

“States must have a role in siting LNG facilities to protect the welfare of their citizens,” said Sen. Dianne Feinstein, D-Calif.

She failed in an attempt to add proposals that would have given governors the right to veto a federal siting decision.

Energy experts predict a soaring growth of LNG imports over the next 20 years to make up for a shortfall of domestic natural gas. Currently, there are only four import terminals. But some 40 new facilities have been proposed; about one-third of them are expected to be built.

“Our biggest challenge is the price of natural gas. More needs to be imported,” said Sen. Lamar Alexander, R-Tenn., a former governor.

Domenici said that a project still would need various zoning, environmental and other permits, and that governors would have input in any siting decision.

“There is no intention in our legislation that local authorities be usurped,” he said.

A report last year by the Sandia National Laboratory concluded that a terrorist attack on a tanker carrying liquefied natural gas would create an intense fire at a terminal. The fire would cause significant property damage and seriously burn people as far as a mile away from the facility.

LNG now accounts for only about 3 percent of U.S. natural gas use. The Energy Department estimates the market share will grow to more than 20 percent by 2025 because of a decline in domestic natural gas supplies.