"If you want to know who's most likely to lead in a serious way on the environment," says Edwards,"look who's been leading throughout the campaign." A former North Carolina senator (and the 2004 Democratic nominee for vice president), Edwards told Iowa voters last March that greening the United States won't be easy, "but it's time to ask the American people to be patriotic about something other than the war."

Battle Cry: "The world is at crisis on the issue of climate change—it requires action now. And without American leadership, nothing will happen."

Green Chops: In March, Edwards became the first candidate to commit to an 80 percent reduction of greenhouse gases by 2050 (a pledge later picked up by candidates Clinton and Obama.) He has demanded a freeze on all U.S. coal-plant development until we find the technology to burn coal with zero emissions.

Power Points: Proposed a plan last spring to auction off greenhouse-gas-pollution permits to help pay for a $13 billion-a-year New Energy Economy Fund, which will be invested in emerging clean-energy industries—a move he believes can create one million "green-collar" jobs by 2025. (Obama later adopted a similar program.)

Outside Moment: Edwards climbed Kilimanjaro with his late son, Wade, in 1995. "Passing a love of the outdoors through generations is a great American tradition," he says, "a powerful reminder of our obligation to act as stewards."

Eco-Hero: "It's a funny thing—today, I actually think it is Al Gore."

Hmmm: Edwards sounds committed, but he showed little environmental leadership during his Senate career, from 1998 to 2004. His 28,200-square-foot home in Raleigh, North Carolina, though equipped with solar panels and other energy-efficient features, casts a long shadow over his conservation rhetoric.