WASHINGTON – The Senate rejected by a wide margin President Bush’s plans for oil drilling in an Arctic wildlife refuge Thursday, turning aside arguments that the oil was needed for the nation’s security.

The vote was a blow to the administration, which repeatedly has cited development of the Alaska refuge’s oil as a centerpiece of its energy policy.

Environmentalists waged an intense campaign to protect the refuge, calling it a unique ecological treasure. Drilling supporters said their proposal contained environmental safeguards.

While the House already has approved legislation to allow development of the oil-saturated coastal plain of the Arctic National Wildlife Refuge, the size of the anti-drilling vote in the Senate may doom any prospect for a drilling measure in Congress this year.

Senate Republicans fell 14 votes short, 54-46, of the 60 needed to break a Democratic filibuster and allow a vote on putting the refuge provision into a broader energy bill.

Eight Republicans, including Sens. Olympia Snowe and Susan Collins of Maine, and Sen. James Jeffords, the independent from Vermont, joined most Democrats in opposing the drilling measure.

“The fastest, cheapest and cleanest step we could take toward reducing our nation’s dependency on foreign oil would be to improve the fuel efficiency of America’s auto fleet – and particularly our biggest gas guzzlers – SUVs and minivans,” said Snowe in explaining her vote against drilling. A bill authored by Snowe to boost fuel economy standards by holding light trucks, SUVs and minivans to the same standard as passenger cars – 27.5 miles per gallon – was killed earlier this year.

In addressing the Senate, Collins said she opposes drilling in the Arctic refuge “because it is both poor energy policy and poor environmental policy.”

“Instead of rushing to deplete what is likely the last major oil reserve in the United States, we should promote energy efficiency and develop alternative technologies,” she said. “Doing so will not only make more of an immediate difference than drilling in the Arctic, but it also will ensure that we leave our children with ample energy supplies and a broader array of energy options.”

Alaska’s two senators, who had led the fight for drilling, expressed disappointment but did not formally withdraw their amendment.

“It’s not over yet,” insisted Sen. Frank Murkowski, R-Alaska. He and Sen. Ted Stevens, R-Alaska, told reporters they planned still other amendments involving the refuge but gave no details.

Democrats said the vote settles the drilling issue, and Republican leader Trent Lott of Mississippi said he expects the amendment to be withdrawn so the Senate can go ahead and pass an energy bill.

Majority leader Tom Daschle, D-S.D., said he hopes to wrap up the energy bill next week, more than a month after the Senate began work on it.

White House press secretary Ari Fleischer said President Bush would continue to fight for opening the refuge to oil development when the matter comes up in negotiations between the House and Senate on a final energy package.

Fleischer sidestepped a question on whether Bush would sign an energy bill that does not include drilling in the refuge. The Senate “missed an opportunity to lead America to greater energy independence,” he said.

Stevens blamed the defeat on senators who succumbed to pressure from “reactionary, radical environmentalists” and ignored the jobs that drilling in the refuge would produce. Murkowski said the votes played into the hands of Iraqi leader Saddam Hussein and other Middle East oil producers.

Some Democrats rejected the national security argument and maintained that had drilling proponents wanted to dampen oil imports, they should have approved increases in automobile fuel economy.

Last month the Senate, by a 63-38 vote, stripped from the energy bill a requirement for automakers to boost fuel economy. The fuel economy increase “would have saved as much oil in three years as is likely to be economically developed in the refuge,” said Sen. Harry Reid, D-Nev.

How much oil is in the refuge is unclear since only one exploratory well has been drilled, on private land within the coastal plain, and its results have been kept secret. Federal geologists believe from seismic studies in the 1980s that the area, just east of the Prudhoe Bay oil field, could yield from 5.7 billion to 11.6 billion barrels of oil. Ten years of preliminary work would be required before production could begin.

The Prudhoe Bay field has produced about 13 billion barrels, and the United States consumes about 19 million barrels a day, 57 percent of it imported.

Bush has argued that the refuge’s oil can be taken without threatening the environment by using modern drilling technology with minimal disturbance of the tundra or risk to wildlife, including 123,000 caribou that use the area as summer calving grounds.

The coastal plain also is used in summer by millions of migratory birds including snow geese. It harbors year around polar bears, musk oxen and other wildlife. A recent Interior Department biological study said caribou and other wildlife could be at risk unless oil development were tightly managed.

“Development would irreversibly damage this natural resource,” said Sen. Joe Lieberman, D-Conn., a leader of the filibuster against the drilling amendment. “Do we want to disrupt its natural state?”