High oil prices are driving a wedge between energy companies and the Cuban-American community, two pillars of support for President Bush and his fellow Republicans.

Companies including Marathon Oil Corporation are lobbying Congress to be allowed to bid for oil and natural-gas deposits in Cuban waters. They are backed by Republican lawmakers bucking Mr. Bush by supporting legislation to exempt the companies from the 1962 trade embargo and a ban on drilling within 100 miles of American shores.

The American need for energy and the likelihood that foreign companies will rush in to drill justifies the exemption, advocates say. “Are we supposed to sit by and let China drill in our backyard?” said Senator Domenici, chairman of the Senate Energy Committee, a co-sponsor with 12 other lawmakers of legislation exempting the American companies.

Cuban-American groups, meanwhile, say the legislation would just prop up the government of President Fidel Castro; if anything, they want the embargo toughened.

“It is an assault on the embargo, masquerading as an attempt to get energy because we need energy,” said Jorge Sorzano, former head of the Miami-based Cuban American National Foundation, the largest anti-Castro group. “It’s hypocritical to want to go into Cuba and help Castro when we won’t even drill in our own waters first.”

American companies have long sought to loosen the embargo. While agricultural restrictions were eased in 2000, other attempts have been defeated by the political power of the Cuban-American community and the desire of both Republicans and Democrats to capture Florida’s 27 presidential electoral votes. This time, though, the combination of public concern over high gasoline prices and the oil industry’s political clout may increase prospects for success.

“When you have a strong domestic industry, whenever they get involved in the embargo, they win,” a Washington attorney who represents American companies with claims against Cuba, Robert Muse, said. “When the farmers got involved in 2000, they won. The energy industry has the same sort of clout, if not more so, in Washington. Plus, when you throw in the gas prices, there’s real pressure.”

The U.S. Geological Survey estimates there may be as many as 4.6 billion barrels of crude oil and 9.8 trillion cubic feet of natural gas in the Northern Cuban basin – roughly equivalent to the estimated reserves in Alaska’s Arctic National Wildlife Refuge, which the Bush administration wants to open to exploration.

Cuba is auctioning 59 lots for exploration, some within 45 miles of Florida. So far, 12 have been sold to Canada’s Sherritt International Corporation and Spain’s Repsol YPF, in partnership with companies from Norway and India.

Sinopec, China’s second-largest oil company, also may bid, said Jose Borges, first secretary of the Cuban Interest Section, which represents the island nation in Washington since America and Cuba don’t have diplomatic relations. Cuba would welcome American companies in the Florida Straits, Mr. Borges said.

Karen Matusic, a spokeswoman for the American Petroleum Institute, the Washington lobbying group for companies such as Irving, Texas-based Exxon Mobil Corporation and San Ramon, Calif.-based Chevron Corporation, said her group supports the exemption legislation “in the context of increasing access to oil and gas reserves as a way to ensure U.S. companies’ competitiveness globally.”

Roger Pinkerton, director of Gulf of Mexico exploration for Houston based Marathon, wrote in a letter that “the North Cuba Basin is just one in a long list of areas offshore where wrong-headed policies of the U.S. government disallow exploration and production.”

Meanwhile, lawmakers representing Florida’s approximately 1 million Cuban-Americans, who form a powerful Republican voting bloc, have introduced measures in the House and Senate that would penalize any foreign company that signs drilling deals with Cuba by barring them from obtaining American business visas and loans.

Mr. Castro, 79, “expresses his hatred of the U.S. every day in every way, and for us to somehow think that to allow U.S. companies to drill, it would be a benefit to the United States, it would not,” said Republican Rep. Ileana Ros-Lehtinen, a sponsor of one of the punitive measures.

“We’re certainly not going to let a megalomaniac, environment-destroying murderer like Fidel Castro drill 45 miles off Florida’s coast,” a board member of the Cuban American National Foundation, Joe Garcia, said.

The Cuban-American lobby has been waiting for more than 40 years for Castro to die or be removed. Barring companies from participating in the development of Cuban oil may put America at a disadvantage when he finally loses his grip, said Rep. Jeff Flake, a Republican of Arizona, who is sponsoring House legislation similar to Domenici’s Senate bill.

“It’s a far more likely scenario that Cubans transition in a way that we would like to see them, to democracy, if they have closer ties to us than to China,” Mr. Flake said. “Who are we kidding here?”