Having spent the last year warring over climate legislation, environmental and industry lobbyists are now facing off over an even higher-stakes trophy: the Clean Air Act and the Environmental Protection Agency's right to enforce it.

Caught in the middle are the three senators who are gearing up to unveil climate legislation soon. Rumor has it that the bill being written by Sens. Lindsey Graham, R-S.C., John Kerry, D-Mass., and Joe Lieberman, I/D-Conn., may include curbs on the EPA's authority to regulate carbon emissions.

That's fired up environmentalists and their allies, which now include such diverse players as human rights, labor, alternative energy and veterans' advocates with climate, economic and national security concerns. Senators drafting the bill have set out to win over oil and gas industry heavyweights, environmental activists argue, but they risk alienating progressive lawmakers who may not vote for a bill that targets the EPA.

"We're certainly concerned about the direction things are going," said Alex Posorske, field and communications manager for 1Sky, a nonprofit coalition that endorses greenhouse gas reductions. Coalition organizers have launched a series of local protests around the country in front of the offices of two dozen House members and senators, urging them to defend the EPA.

Early signals suggest that the bill may include firm targets for cutting greenhouse emissions over the next 10 years, but it may also propose subsidies for nuclear energy production, along with curbs on the EPA's authority to regulate carbon emissions. The EPA has become a line in the sand for lobbyists on both sides of the climate debate.

In December the EPA declared that global warming gases pose a threat to human health and welfare, setting the stage for new regulations slashing emissions from both cars and trucks, and from power plants powered by coal, oil and gas.

Some on Capitol Hill have lashed back with measures that challenge the EPA's right to regulate greenhouse gases under the Clean Air Act. These include a disapproval resolution authored by Sen. Lisa Murkowski, R-Alaska, that would overturn the EPA's finding that the gases pose a health danger; and a bill dropped by Sen. Jay Rockefeller, D-W.Va., that would block the EPA from curbing greenhouse emissions from power plants for two years.

For energy industry players, reversing the EPA on greenhouse gases may be non-negotiable. Graham has suggested that business leaders won't back the climate bill without it, and neither will key senators. After the House passed a cap-and-trade climate bill last June, the American Petroleum Institute launched a high-dollar ad campaign blasting it as a boondoggle that would tax oil and gas companies and send jobs overseas. Graham and his allies may hope to forestall a repeat performance.

"Our big problem is with EPA," said Lou Hayden, senior director of federal relations for the American Petroleum Institute. "Programs written to cover traditional pollutants are a big problem when they are applied to greenhouse gases."

The API spent $7.3 million on lobbying last year, a 52 percent increase over its $4.8 million lobbying total in 2008, according to the Center for Responsive Politics. Overall, the oil and gas industry spent $168 million on lobbying in 2009, up from $133 million in 2008, CRP data shows. The industry and its allies have gotten a big assist from the U.S. Chamber of Commerce and the National Association of Manufacturers.

The climate fight continues to feature fluid and sometimes unpredictable coalitions. The U.S. Climate Action Partnership brought together environmental and industry leaders in a broad umbrella group to campaign for climate legislation, but some oil and gas companies have peeled off. The U.S. Chamber has squabbled with some of its members over climate policy.

In the meantime, a coalition of nonprofits dubbed Clean Energy Works has mounted an extensive field operation that includes activists of all stripes, from religious organizations to civil rights groups and veterans. One member organization, VoteVets.org, has spent upwards of $5 million on a lobbying and advertising campaign to promote climate legislation, said its chairman, Jon Soltz.

"Certainly we're up against big oil, and that's a fight we welcome," said Soltz. Along with the Truman National Security Project, VoteVets.org has mounted two bus tours to promote climate legislation, which Soltz argued is more of a national security than an environmental issue: "Our troops are literally getting killed every day because of our addiction to oil."

For the moment, however, the EPA has become ground zero in the climate wars. Environmentalists in particular reject the premise that the Senate will only enact climate legislation in exchange for stripping the EPA of its power. Many regard the Clean Air Act as the signal accomplishment of the environmental movement.

Leading environmental and progressive groups, including the Sierra Club and MoveOn.org, have joined 1Sky in a lobbying blitz aimed at convincing lawmakers to defend the EPA. Until now, all the trial balloons floated in the Senate appear calculated to win over fossil fuel lobbyists. But the dynamic may flip if the Graham-Kerry-Lieberman bill becomes a vehicle to curtail the EPA. As Posorske put it: "We may very well be nearing a line that raises a red flag for progressives."

(Cross posted from NJ.com)