Washington ? The renewed push for legislation to cut greenhouse gas emissions could falter over an old debate: whether nuclear power should play a role in any federal attack on climate change.

With added impetus from a Supreme Court decision last week, Congress appears much more likely to pass comprehensive legislation. But nuclear power sharply divides lawmakers who otherwise are on the same side in supporting mandatory caps on carbon dioxide emissions. And it has pitted some on Capitol Hill against their usual allies, environmentalists, who largely oppose any expansion of nuclear power.

House Speaker Nancy Pelosi and Sen. Barbara Boxer – California Democrats with similar political views – are now on opposite sides.

Pelosi once was an ardent foe of nuclear power but now holds a different view. “I think it has to be on the table,” she said.

But Boxer, chairwoman of the Senate committee that will take the lead in writing global warming legislation, contends turning to nuclear power from fossil fuels is simply “trading one problem for another.”

Sens. John McCain, R-Ariz., Barack Obama, D-Ill., and Hillary Rodham Clinton, D-N.Y. – all presidential candidates – are among the influential lawmakers who support legislation that would cap greenhouse gas emissions but provide incentives to power companies to build more nuclear plants.

Opponents of nuclear power say a terrorist attack on a plant could be catastrophic, so it makes no sense to build more potential targets. And, they point out, there still is no permanent burial site for radioactive waste, despite three decades of trying to find one.

But attitudes toward nuclear power may be shifting as a consensus emerges that greenhouse gases are causing the world to heat up.

The Supreme Court added its voice, criticizing the Bush administration for failing to act to control greenhouse gases. Max Schulz, a former Energy Department staffer who is a senior fellow at the Manhattan Institute – a conservative think-tank – said the ruling could help “spur the revival of nuclear power.”

And congressional Democratic leaders have made passage of global warming legislation a priority for the two-year session.

“I’ve never been a fan of nuclear energy,” said Sen. Dianne Feinstein, D-Calif., who in the past has called it expensive and risky. “But reducing emissions from the electricity sector presents a major challenge. And if we can be assured that new technologies help to produce nuclear energy safely and cleanly, then I think we have to take a look at it.”

The public also appears more favorable toward nuclear power when it is viewed as part of an effort to fight climate change. Polls over the years have shown a slim majority backs nuclear power, but a Los Angeles Times/Bloomberg survey last summer found 61 percent of the respondents support increased use of nuclear energy “to prevent global warming.”

“There’s no question that the attention to climate change over the last several years has materially changed the public discussion of nuclear power,” said Jason Grumet, executive director of the National Commission on Energy Policy, a bipartisan group of energy experts. Given the threat of global warming, he said, “it’s hard to ignore the principal source of noncarbon power generation in the country today.”

The U.S. nuclear power industry has been at a virtual standstill because of high construction costs, regulatory uncertainties and public apprehension after the 1979 accident at Pennsylvania’s Three Mile Island. A number of plants – ordered before the accident – went into operation afterward. But many more were canceled after one of the Three Mile Island reactors suffered a partial meltdown and very small amounts of radiation were released to the atmosphere.

Currently, 103 nuclear power plants generate about one-fifth of the nation’s electricity.