NEW YORK (CNN) -- Former Vice President Al Gore said he has "fallen out of love with politics" and has no intentions of running for office again.

Former Vice President Al Gore said the only campaigning he wants to do is against global warming.

"I'm involved in a different kind of campaign, not for myself not as a candidate, but to change people's minds about the most dangerous crisis we've ever faced, and the greatest set of opportunities we've ever confronted to solve this climate crisis," he told CNN's Larry King on Thursday.

When asked on NBC's "Today Show" why he wouldn't run for president again -- when presumably a president could shape an agenda to fight global warming -- Gore said those in power must have the support of the people to make it work.

"The key players are the American people," he said. "When the American people have the awareness of what this means for their children, and for their grandchildren, that all of civilization is at risk here, then they will demand that whoever is running for office, whoever is elected to serve, will have to respond to this."

Despite Gore's stance, many grassroots movements, with Web sites such as AlGore.org and draftgore2008.org, are trying persuade him to run.

"Americans from every corner of our nation are calling on you," reads a petition on Draftgore.com. "Please listen to our plea and run for the Democratic nomination for the presidency of the United States in 2008." The petition has has nearly 100,000 signatures.

And according to a recent CNN poll, Gore is the choice of 16 percent of likely Democratic voters, putting him in third place, behind Sen. Hillary Clinton (35 percent) and Sen. Barack Obama (23 percent).

Gore refused to endorse any candidate, saying that the election is 500 days away.

Gore has stopped short of closing the campaign door, but he has left little room to expect anything else.

"I've kind of fallen out of love with politics. ...Whatever experience and talents I've gained over the years -- I think it may well be that the highest and best use of that is to try to bring enough awareness of the solutions to the climate crisis and enough of a sense of urgency that we come together across party lines on behalf of our children," Gore said.

After 16 years in Congress, Gore was vice president under President Bill Clinton from 1993 to 2001.

He was the Democratic nominee for president in 2000, losing to President Bush after a lengthy legal fight over voting results in Florida. Gore toyed with the idea of a rematch against Bush in 2004, but decided against it.

Gore was making TV appearances to discuss Saturday's "Live Earth" concerts, which will be broadcast by NBC. Watch Gore discuss his campaign with Larry King »

The purpose of the event is to "trigger a global movement to solve the climate crisis," according to the Live Earth Web site. E-mail to a friend

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