For former Vice President Al Gore, a rash of favorable publicity surrounding this month's opening of his movie "An Inconvenient Truth," and the growing political resonance of its subject - global warming - are stoking the most serious speculation about a Gore political comeback since his loss in the 2000 U.S. presidential election.

In 2008, that could mean a once-unimaginable battle for Democrats' nomination between Bill Clinton's former vice president and his wife, Hillary Clinton. To some pro-Gore Democrats, worried about Mrs. Clinton's electability, that is part of the appeal.

"I appreciate that buzz, but he's not running for president," insists Michael Feldman, a former vice presidential adviser who is helping promote the film and Mr. Gore's new book on which it is based. "He has been spending a considerable amount of time trying to educate people about the issue of global warming," and won't talk about politics "right now," Mr. Feldman says.

The demurrals aren't persuasive to some Democrats, including former Clinton-Gore White House insiders. "I do know that he's thinking about it. I know for a fact," a former adviser says. "He's talked to people about the pros and cons."

Among those said to be pushing Mr. Gore are billionaire venture capitalist and high-tech entrepreneur John Doerr and Laurie David, a global-warming activist and producer of the film, and wife of "Seinfeld" and "Curb Your Enthusiasm" creator Larry David. "When people see this movie, I know they're going to see the real Al Gore, and they're going to demand that he run," Ms. David says. But, she adds, he changes the subject whenever it comes up, and had to be talked into making the movie when she pitched it.

Mr. Gore has begun assembling a Nashville, Tenn.-based operation to help with the demands on his time. He has hired longtime friend and top aide Roy Neel to head the office, and environmental activist Kalee Kreider, from a Washington public-relations firm, to handle communications. Mr. Feldman says their work will focus on global warming, not on maneuvering for 2008.

Yet the talk of a political second act for the man who won the 2000 popular vote, but lost in the Electoral College after a U.S. Supreme Court ruling, exceeds anything before 2004, when Mr. Gore could have sought a grudge match against President Bush.

In recent weeks, he has been on the covers of Vanity Fair, Wired (its headline: "The Resurrection of Al Gore") and American Prospect, a liberal Democratic magazine. Defeated politically, he nonetheless makes Time's list of the world's 100 most influential people; Mr. Gore is featured under the headings "Heroes and Pioneers" and "America Takes a Fresh Look at 'Ozone Man'" - the derisive nickname coined by the first President Bush in 1992 after Mr. Gore's previous environmental book, "Earth in the Balance," came out.

"His star will never be higher than it is right now with his movie coming out," says Democratic consultant Karen Skelton, Mr. Gore's former political director.

The Gore buzz reflects a sense among even some pro-Clinton Democrats that Mrs. Clinton, considered the prohibitive favorite for the nomination given her support in the party's base of activists and donors, can't win the general election because she is a polarizing figure to many voters. These skeptics believe only someone such as Mr. Gore with the celebrity and fund-raising potential to match Mrs. Clinton could stop her.

Like Mrs. Clinton, Mr. Gore remains a negative figure to many voters, says a Democrat who has seen private polls. For both, that might only increase with the spectacle of a Clinton-Gore brawl. Even insiders can't fully account for the bad blood that has built up since. At bottom, they say, it reflects contrasting views of what cost Mr. Gore the 2000 election: Mr. Clinton's scandals, or Mr. Gore's decision to so fully separate himself from a president who remained popular amid peace and prosperity. Several insiders say Mr. Gore is more likely to run if Mrs. Clinton does than if she doesn't.

Also controversial among Democrats was Mr. Gore's 2004 endorsement of Howard Dean, now the Democratic Party chief, just as Mr. Dean was stumbling in his presidential primary race against the ultimate nominee, Massachusetts Sen. John Kerry. Mr. Kerry also is considering another run in 2008, though he, like Mr. Gore, would have the taint of a loser for partisans craving a fresh face.

According to Mr. Feldman and others, Mr. Gore is enjoying his freer and more lucrative life as a private citizen. "My expectation is he's not going to run in 2008," says Tad Devine, a top Gore strategist in 2000 who hasn't spoken with him lately. "He's in a really good place, and he's succeeding fabulously. Why would he want to walk away from it all?"

Mr. Gore and his wife, Tipper, have a new home in an affluent Nashville area, and they recently bought a condominium in San Francisco, nearer to two daughters in California. Since conceding to Mr. Bush, he has taught at several universities and written two books with his wife. He is on Apple Computer Inc.'s board and is senior adviser to Google Inc. He has founded Current, a youth-oriented, interactive cable network, and Generation Investment Management, which invests in companies deemed environmentally and socially responsible.

Periodically he has spoken out against Mr. Bush on the environment, Iraq and alleged abuses of executive power, in speeches promoted by the liberal group MoveOn.org. And he has widely given the 90-minute lectures and computer slide shows on global warming that, for all his reputed stiffness, gave rise to a film that drew standing ovations at the Sundance Film Festival.

On stage and in the film, a deadpan Mr. Gore opens, to laughs and applause: "I am Al Gore. I used to be the next president of the United States of America."

Mr. Gore, who turns 60 in 2008, could remain noncommittal and enter the presidential fray late, given his fame and fund-raising potential - unlike lesser-known Democrats already stumping in the early-nominating states to be the Clinton alternative, such as former Sen. John Edwards of North Carolina, former Virginia Gov. Mark Warner, Iowa Gov. Tom Vilsack, and Indiana Sen. Evan Bayh. If Mr. Gore ran - or were drafted, as Ms. David suggests - the longtime Washingtonian would run as an outsider, Democrats expect, helped along by his relationship with Internet-savvy MoveOn.org activists.

There would be no small irony in Mr. Gore re-emerging with a crusade against global warming. In 2000, he played down the issue he had so long been identified with in Congress, on his consultants' advice. They feared the younger Bush, like his father, would use the issue to reinforce an image of Mr. Gore as a bloodless wonk, and make it a jobs question for voters in swing industrial and coal-mining states. "The campaign took this issue off the table and robbed him of seeming 'big' and visionary," says former Clinton White House Chief of Staff John Podesta. "I think he regrets that."