Al Gore has had plenty of time to develop a self-deprecating sense of humour over the past six years, and it shows. "My name is Al Gore, and I used to be the next president of the United States," the broad-shouldered 58-year-old tells audiences wherever he goes.
The line has replaced an earlier joke - "You win some, you lose some, and then there's that little-known third category" - but the message in both cases is the same: laugh along with me, please, because otherwise, imagining how different things could have been, we might have to cry.
It is a wry kind of wit, of a sort that might have helped the former vice-president in the 2000 election campaign, when he was widely lambasted as wooden and robotic. And it is tinged with an anger that might have come in handy during the supreme court battle with George Bush, when many of Mr Gore's own supporters felt he acted spinelessly. But the Gore of 2006 is a different person and, it appears, Americans have begun to take notice.
The reason for Mr Gore's heightened profile is a documentary about his most passionately held concern - the "planetary emergency" of global warming - that he has been shopping to politicians and other opinion-formers over the last few weeks. (On Wednesday, he showed it to members of Congress; next week the Gore roadshow crosses the Atlantic for the Guardian Hay Festival.)
Shock to the core
The movie, An Inconvenient Truth, is released in the US next Friday, a week after The Da Vinci Code, and its trailer seems to be straining every nerve to compete. "It will shock you to your core," the captions read. "By far the most terrifying film you will ever see."
The film follows Mr Gore as he travels the US giving a slideshow presentation about climate change - a performance he has given more than a thousand times in the past 30 years, and more frequently since losing the election.
This may sound less than electrifying, but there could be no better sign of the film's potential impact than the fact that its enemies have launched a counter-offensive: the Competitive Enterprise Institute, a rightwing thinktank funded by oil companies, has unveiled a series of TV advertisements aimed at restoring the reputation of greenhouse gases.
"The fuels that produce carbon dioxide have freed us from a world of backbreaking labour, allowing us to create and move the things we need and the people we love," a syrupy voice intones, over footage of children playing. "Carbon dioxide: they call it pollution. We call it ... life."
As the early rumblings of the next presidential election campaign grow louder, it should come as no surprise that Mr Gore's activities have led to speculation that he might run again. He denies it, saying that he has "found other ways to serve", but that has not stopped the rise of a vigorous draft campaign to try to persuade him to change his mind, a strategy that worked in 2004 with General Wesley Clark.
Recovering politician
The drafters' pulses were quickened by a recent Gore speech when he joked that he was "a recovering politician ... but you always have to worry about a relapse", while an appearance on the comedy show Saturday Night Live, where he addressed the audience as if he had been president for a term and a half, only added to their excitement.
The crucial change in Mr Gore's outlook arises from the bitter fights he had in 2000 with his own consultants. Obsessed by polls, they persuaded him to water down his proposals on climate change so much that the man who had helped negotiate the Kyoto protocol ended up doing little more than railing against the high price of petrol.
"He held a meeting about a year and a half after his campaign was over, with his closest supporters, and he said, 'If I ever do this again, it's going to be without consultants - I'm going to say what's on my mind,'" said the veteran political columnist Joe Klein, "and he's been pretty much that way ever since." (Almost uniquely among prominent Democrats, for example, Mr Gore vocally opposed plans for attacking Iraq long before the invasion.) "But is this a precursor to a left-populist campaign against Hillary Clinton, or is he just stumping on something he really cares about?" wondered Mr Klein. "I don't know."
The alternative, non-presidential theory is that Mr Gore has found his niche. In 2000, he failed to pass the pollsters' "barbecue test": the average American voter, it was argued, would far rather have had Mr Bush over to their home for an evening of beer and hamburgers. But in global warming, he may have found a cause where the barbecue test is irrelevant.
"This is a problem that's amenable only to government technical solutions," said Gavin Schmidt, a Nasa climatologist who helped Mr Gore design the slideshow on which An Inconvenient Truth is based. "I'd say the level of general awareness is as high as it's going to get ... Gore's aim is to take the details to the people who can really make the decisions."
He might be advised to keep working below the radar of electoral politics. In America, "we love everybody up to the moment they declare their candidacy, and love them again once they lose, but while they're a candidate we generally beat the hell out of them," said Jeffrey Toobin, who watched Mr Gore at close range for his book on the 2000 election, Too Close To Call. That feeling would be unlikely to survive exposure to the open warfare of a US election campaign - a fact that must be, for any part of Mr Gore that still craves the presidency, its own kind of inconvenient truth.
