NEW YORK — T. Boone Pickens leans forward in his chair to better hear Al Gore exhort solar and wind power at the National Clean Energy Summit in Las Vegas. Pickens, who made and lost billions betting on energy in his boom-and-bust career, waits with Democratic Party bigwigs for his turn to speak. His topic: why the U.S. must wean itself from foreign oil.

It's a far cry from the wildcatter turned corporate raider and backer of fellow Republican oilman George W. Bush, who downplayed global warming as U.S. president. Now Pickens has ingratiated himself not only with environmentalists but with the Democrats who derided him. The reason: his Pickens Plan, which embraces natural gas and wind power and which proponents say would cut oil imports and curb air pollution in the process.

"A year or so ago, I started taking missionary lessons from the group supporting T. Boone Pickens," Democrat Harry Reid told the 900-strong audience.

Reid, the U.S. Senate majority leader, had called Pickens his "mortal enemy" for funding Swift Boat Veterans for Truth. The group's attack ads helped sink the presidential bid of Massachusetts Senator John Kerry and hand Bush a second term from 2005 to 2009.

"I now belong to the Pickens church," Reid said. "He's been a good friend and a real visionary."

By dint of his plan, which Pickens has scaled back to focus on using natural gas to power the nation's 6.5 million diesel-burning heavy trucks, he has transformed himself into an unlikely environmental hero. Pickens says the U.S. can save 2.7 million barrels of oil a day, more than half of the 4.3 million barrels a day it imported from OPEC in June.

After spending $60 million and taking a yearlong swing across America, Pickens, 81, has amassed enough support to persuade both Republicans and Demo[0xad]crats to propose legislation that gives incentives for natural gas vehicles and fueling stations.

An energy bill, with bipartisan backing, is likely to pass in some form, increasing U.S. interest in natural gas, says Scott Deatherage, a partner at Thompson & Knight LLP in Dallas, who advises corporations on environmental regulation.

People who see only Pickens' past need to get beyond that and look at his ideas, says Dan Weiss, senior fellow at the Center for American Progress.

"His plan is on the right track," he says. "Pickens has gotten off oil, and his plan will reduce foreign oil consumption and clean the air."

Pickens warns that oil may reach $150 a barrel in the next two years as economic activity rebounds to pre-recession levels. The petroleum industry will have trouble raising production fast enough to meet demand, he says. And even if it could, it would mean the U.S. would continue funding foreign governments by buying their output.

"Show me another country where they import 70 percent of their oil and over half comes from their enemy," Pickens says, counting Iran, Saudi Arabia and Venezuela among the foes. "This is the largest transfer of wealth in human history."

Pickens says natural gas can move America toward energy independence. He cites statistics from the nonprofit Potential Gas Committee, which indicate that the United States' supply can last 100 years. Gas produces as much as 30 percent less carbon dioxide than oil when burned, according to the U.S. Energy Department.

"Natural gas is clean, it's cheap and it's ours," Pickens says.

Not everyone is convinced that Pickens has abandoned his old maneuvers. Critics say he wants to shore up his investments and is cloaking his strategy in the American flag.

For one thing, he holds a 33 percent stake valued at about $275 million in Clean Energy Fuels Corp., a Seal Beach, Calif.-based company he founded. The company, which runs 184 natural gas filling stations, would benefit from proposed federal legislation for which Pickens has lobbied.

"The Pickens Plan is nothing more than a call to rig the market toward the fuels that Pickens has invested in," says Jerry Taylor, a senior fellow at research group Cato Institute.

Pickens has never lacked for big plans. He says he has at least one more thing to accomplish. "I'm trying to fix the country," he says.