The environmental movement must become "hip and sexy" if it is to succeed, California's Governor Arnold Schwarzenegger has said.
By Laura Smith-Spark
BBC News, Washington
Speaking at a conference in Washington, he urged campaigners to focus on the positives of cutting carbon emissions rather than making people feel guilty.
The movement must change its image just as he helped transform the "sketchy" reputation of bodybuilding, he said.
California is seen as leading the way in tackling climate change in the US.
The state - the sixth largest economy in the world - signed a law last year that set a target of cutting its greenhouse gas emissions by 25% by 2020.
And while Mr Schwarzenegger cannot stand for president in 2008 because he is not US-born, he has made it clear he wants his views on climate change to play into the race.
Addressing a largely student audience at Georgetown University, Mr Schwarzenegger said he was optimistic attitudes to the environment were changing.
Environmentalism must become hip and sexy, Mr Schwarzenegger says
But, he said, campaigners on climate change needed to shake off the image of being "tree-huggers" and "fanatics".
"Environmentalists were no fun; they were like prohibitionists at a fraternity party," he said to laughter.
The Republican governor - the former body-builder turned film-star turned politician - invoked images of "pumping iron" to make his point.
Weight-lifting was once considered a pursuit for weirdos, he said, carried out in dungeon-like gyms by people embarrassed to admit to doing it.
But with positive marketing "it became mainstream, it became sexy, attractive, and this is exactly what has to happen with the environmental movement", he said.
The same thing happened when the John Travolta film Saturday Night Fever made disco-dancing hip and sexy, he added, reaching even his little village in Austria.
Mr Schwarzenegger, who has been criticised in the past over his fleet of Hummers, pointed out that his vehicles now run on bio-fuel and hydrogen.
"We don't really want to go and take away the 'muscle' cars, the Hummers and the SUVs, because that's a formula for failure," he said.
"What we have to do is make those cars more environmentally muscular."
He rebuffed criticism from US carmakers, saying the fact they had to meet Californian standards on vehicle emissions would ensure they kept up with foreign competitors.
And he urged campaigners to move away from using guilt to pressure people over greenhouse gas emissions.
"Successful movements aren't built on guilt, they are built on passion," he said.
He believes the environmental movement is approaching a "tipping point" where it will enter the mainstream, galvanising business and individuals.
And California was leading the way, Mr Schwarzenegger said, especially as Republicans and Democrats were working together to pass pioneering legislation on the environment.
"California is big, it's powerful and what we do in California has unbelievable impact and it has consequences," he said.