WASHINGTON — A closely divided Senate voted Wednesday to approve oil drilling in an Alaska wildlife refuge, a major victory for President Bush and a stinging defeat for environmentalists who have fought the idea for decades.

By a 51-49 vote, the Senate put a refuge drilling provision in next year's budget, depriving opponents of the chance to use a filibuster to try to block it. Filibusters, which require 60 votes to overcome, have been used to defeat drilling proposals in the past.

"This project will keep our economy growing by creating jobs and ensuring that businesses can expand," Bush said in a statement. "And it will make America less dependent on foreign sources of energy, eventually by up to a million barrels of oil a day."

Utah's Republican Sens. Orrin Hatch and Bob Bennett favor opening the preserve to drilling. Their votes drew criticism from the Utah Democratic Progressive Caucus. "If the current administration and Republicans in Congress were serious about reducing our reliance on foreign oil, they would aggressively pursue improvements to automobile fuel efficience, said Craig Axford, co-chairman of the UDPC.

Sen. Ted Stevens, R-Alaska, who has fought for 24 years to open the Arctic National Wildlife Refuge to oil companies, acknowledged it still could be "a long process" before a final drilling measure clears Congress. Lawmakers must agree on the final budget, something they failed to do last year, or Wednesday's vote would have been for naught.

Also, the House did not include an Arctic refuge measure in its budget, a difference that will have to be worked out in future negotiations.

Nevertheless, the Senate made clear by Wednesday's vote that a majority now supports tapping what is believed to be 10.4 billion or more barrels of oil within the refuge's 1.5 million-acre coastal plain, said Sen. Lisa Murkowski, R-Alaska. Two years ago, a similar attempt to use the budget process to open the refuge failed by three votes.

But that was before Republicans last November expanded their majority, adding a number of GOP senators who favor drilling. Only seven Republicans, all moderates, bucked their party Wednesday and voted with most Democrats against opening the refuge.

Environmentalists said while the vote was disappointing, they haven't given up the fight. "It only strengthens our resolve to protect America's most pristine national wildlife refuge for our children's future," said Larry Schweiger, president of the National Wildlife Federation.

"The battle is far from over," said Lexi Keogh of the Alaska Wilderness League. She said environmentalists will push to keep the ANWR provision out of a final budget document.