WASHINGTON (AP) – Congress on Thursday moved a step closer to opening an Alaskan wildlife refuge to oil drilling as House and Senate Republicans reached agreement on a budget outline that could be used to consider the issue without the threat of a filibuster.

Opponents of oil development in the Arctic National Wildlife Refuge repeatedly have used the filibuster, which requires 60 votes to overcome, to block action in the Senate.

But legislation that reconciles government spending with the budget is immune from filibuster and, therefore, can be approved by a simple majority vote.

The budget resolution agreed to Thursday among Republicans does not mention the Alaska refuge. But the resolution requires that lawmakers in both the House and Senate abide by certain spending cuts and revenue amounts when they develop spending proposals.

House and Senate committees have to come up with $2.4 billion in net revenue under the budget directive. The Interior Department puts the anticipated money from bonus bids for leases in the refuge also at $2.4 billion.

Sen. Pete Domenici, R-N.M., chairman of the Senate Energy and Natural Resources Committee, has said that he will include expected revenues from oil lease sales in the refuge to help meet the budget requirements. Such a move essentially would authorize drilling there.

It is not certain the House would follow the Senate’s lead.

The chairman of the House Resources Committee, GOP Rep. Richard Pombo of California, has not decide whether to turn to the refuge to meet that budget obligations, said his spokesman, Brian Kennedy.

Last week, the House approved a broad energy bill that also includes authorization to open the Alaska refuge’s coastal plain to oil companies. But in the Senate that legislation is certain to run into trouble because it is subject to a filibuster. Domenici does not plan to include the refuge drilling in a Senate energy bill.

House GOP leaders strongly support developing oil there. But they also want to limit the number of times the issue has comes up for a floor vote, fearful of losing the support of moderate Republicans on the issue.

The House may wait until negotiations with the Senate on a final budget reconciliation plan – probably in the fall – before agreeing to include the drilling proposal. This would require only one House floor vote about the refuge as part of the budget process.

President Bush on Thursday reaffirmed his support for drilling in the refuge, where the government estimates there are about 10.4 billion barrels of oil beneath a 1.5 million acre coastal plain. Peak production is expected to be 1 million barrels a day.

The United States last year used 20.5 million barrels of oil a day, about 58 percent of it from imports. Bush said the United States needs oil from the refuge to help curtail reliance on imports.

But many Democrats and some moderate Republicans want to continue fencing off the refuge from oil companies, fearing that exploration, followed by oil development, will harm the refuge’s ecosystem and an array of wildlife from polar bears and caribou to millions of migratory birds. They also maintain the oil in the refuge would have little impact on oil imports or prices.