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He knows he doesn't have the votes to win, yet Sen. John McCain (search) is determined to challenge President Bush head-on over global warming by pushing for a Senate vote on climate change.

It would be the first public expression of the Senate on the issue since just before the Kyoto (search) climate treaty was drafted six years ago.

Even if he loses, McCain says, he will win.

And the Arizona Republican isn't bothered that his partner in the effort is Sen. Joe Lieberman of Connecticut, who is seeking the Democratic nomination for president.

"We've got to get the (climate) debate on the record," McCain said in an interview. "We've got to build public support."

It will be a beginning, he predicts, comparing it to the early days of his fight to overhaul the nation's campaign finance laws, an effort that eventually bore fruit.

Adding to the buzz are the presidential campaign overtones.

"It's critically important ... to get a vote," Lieberman agrees, no matter what the results.

The McCain-Lieberman amendment would set limits for the first time on emission of greenhouse gases, especially carbon dioxide that comes from burning fossil fuels. The Bush administration, while endorsing voluntary efforts to reduce heat-trapping emissions, has opposed mandatory limits, arguing that such restrictions would be too costly when the science of climate change is still uncertain.

The climate issue may come to the Senate floor as part of the energy debate as early as Thursday.

Powerful interests - energy companies, the U.S. Chamber of Commerce (search), electric utilities and manufacturing interests - have been lobbying against the measure, producing studies that claim limits on carbon dioxide would cost tens of billions of dollars and cause havoc at a time when the country is dealing with a growing shortage of natural gas.

It "will put us out of the fossil fuel business," Sen. Craig Thomas, R-Wyo., said Wednesday.

McCain and Lieberman argue that the threat of climate change is real and some actions to curtail carbon dioxide emissions are overdue. They reject the idea that addressing the climate issue will hurt the economy.

Meeting new emissions reductions would produce more high-tech jobs and show other countries "we're serious about this global problem," Lieberman argues.

The amendment would require that by 2010 U.S. industry cut back the amount of heat-trapping carbon dioxide released into the atmosphere to what it was in 2000, reversing a trend of annual increases. To reduce costs industry could use a market-based emissions trading system.

By comparison, the Kyoto climate accord, crafted in December 1997 - but never ratified by the United States and rejected by Bush - would have required the United States to reduce greenhouse gas emissions to 7 percent below 1990 levels by 2012.

Bush has abandoned any intention of actually reducing emissions and has set a goal of cutting into the rate of carbon dioxide growth. Last week, the administration produced a 10-year plan to re-examine the science of climate change, saying there are too many unknowns about the issue.

"Too much attention has been focused on uncertainties and not enough on what is known," McCain argues.

The White House strongly opposes any climate amendments to the energy bill that "are inconsistent with the president's climate change strategy," according to an administration policy paper.

Environmentalists long have waited for senators to commit on the record their views on the global warming.

"This amendment will be a full-fledged debate about climate," says David Doniger, policy director of the Natural Resources Defense Council (search). "Lots of members (of Congress) have been hiding on this issue. Now they have to take a position."

The last time they did was a few months before the pivotal 1997 climate conference in Kyoto, Japan, on a Senate resolution that urged U.S. negotiators to reject an agreement that did not include commitments from developing countries or which would harm the U.S. economy.

It passed 95-0 and has been used ever since by critics of the Kyoto accord as congressional repudiation of the agreement, although the Senate never actually considered whether to ratify the treaty.

Opposition to Kyoto remains widespread in Congress and some senators question the validity of global warming altogether.

"This whole idea of global warming is something that has been brought up by certain groups that have a lot to benefit from it and has nothing to do with real science," Sen. James Inhofe (search), R-Okla., chairman of the Senate Environment Committee, told reporters Wednesday.