Washington ? Republican gains in the Senate could give President Bush his best chance yet to achieve his No. 1 energy priority — opening an oil-rich but environmentally sensitive Alaska wildlife refuge to drilling.

If he is successful, it would be a stinging defeat for environmentalists and an energy triumph that eluded Bush his first four years in the White House. A broader agenda that includes reviving nuclear power, preventing blackouts and expanding oil and gas drilling in the Rockies will be more difficult to enact.

Republicans in the House and Senate said this week they plan to push for Alaska refuge drilling legislation early next year, and they predict success, given the 55-44-1 GOP Senate majority in the next Congress. Democrats and some environmental activists say continued protection of the refuge has never been as much in doubt.

Sen. Pete Domenici, R-N.M., chairman of the Senate Energy and Natural Resources Committee, said he will press to open the coastal plain of the Arctic National Wildlife Refuge (ANWR) as part of the government’s budget deliberations early in 2005.

“With oil trading at nearly $50 a barrel, the case for ANWR is more compelling than ever,” said Domenici. “We have the technology to develop oil without harming the environment and wildlife.”

Bush also expected in his second term to renew his call for action by Congress on a broader, largely pro-production, energy agenda — from easing rules for oil and gas drilling on federal land in the Rocky Mountains to expanding clean-coal technology and improving the reliability of the electricity grid.

New tax incentives to spur construction of next-generation nuclear power plants also will be back on the table after Democrats and some moderate Republicans scuttled it last year. Greater use of corn-based ethanol in gasoline also has wide support at the White House and in Congress.

Environmentalists already are gearing up to wage an intense lobbying campaign to keep oil rigs out of the refuge’s coastal plain, a breeding ground for caribou, home to polar bears and site of an annual influx of millions of migratory birds.

“This is as serious a threat to the refuge as any that has come before,” said Jim Waltman of the National Wildlife Federation. “But the facts haven’t changed. This is still a magnificent area and it can still be damaged by oil drilling.”

Geologists believe 11 billion barrels of oil lie beneath the refuge’s tundra and ice.