Former Vice President Al Gore, delivering a speech in Washington on environmental issues, said global warming, not terrorism, is the No. 1 threat to America.
While he praised both Sens. Barack Obama and John McCain for their stands on environmental issues, Gore challenged the next president to take bold steps to solve the problem.
"Both are serious and must be addressed. That having been said, I think that the climate crisis is, by far, the most serious threat we have ever faced," Gore told ABC News' Claire Shipman after the speech.
The one-time presidential candidate said Thursday that within 10 years, the United States should be able to produce all of its electricity with earth-friendly, carbon-free power.
Some critics have called Gore's ambitious plan an unachievable pipe dream. After Gore's speech, Obama issued a statement praising his idea. McCain said that while he and Gore differ on some environmental issues, he agrees that the country needs to move toward more solar and wind power.
While Gore has endorsed Obama for president, some Democrats wonder why he is also complimenting McCain, especially as McCain has become a vocal supporter of President Bush's call for more oil drilling.
"Well, I've endorsed Barack Obama. I'm a Democrat. But I think that John McCain deserves credit for having provided some leadership in the Republican Party years ago at a time when it was needed," Gore said.
Gore also said he is not on a short list for vice president, but didn't rule out a Cabinet position in either future administration.
"You're looking at a different list than I am. I've decided to impose a personal term limit of two terms as vice president," Gore told Shipman.
When asked about becoming an environmental czar for McCain or Obama, Gore joked, "Now the title of czar is intriguing."
Gore, who last year won a Nobel prize for his work on the environment, seems content with a role outside the political process.
"In all seriousness, I do see my role as one that's focused on changing public opinion," he said.