At 70, without a thing left to prove, Jack Nicholson is sharpening his political edges. Not that he’ll be showing up at any presidential campaign rallies. “I, by choice, am not an activist at this point,” Nicholson said. “I think Sean Penn is the greatest living American in a certain way, because he’s a man of action. I feel by being a neutralist in this area, in my actual field of endeavour I can be more effective.”

That didn’t stop the icon of Hollywood cool from talking of solar power, Tony Blair, oil industry propaganda and his friendship with the Clintons. Cooly, of course.

“You do not become militant if you wish to be a successful propagandist. Because all you will do is preach to the choir and further entrench your opposition.”

That’s worth a signature Jack eyebrow arch. But while he hints at folding progressive messages into his movie roles, Nicholson in conversation also has the crowd-pleasing ability of a natural actor to take both sides of an issue and make you believe him.

He calls former British Prime Minister Blair a “rock star... he’s wonderful” and says he supports Hillary Clinton in the presidential race (“I’m a friend of the family”). Nicholson acknowledges being “a lifelong Irish Democrat. What more can I say? I voted for what’s his name, (1988 presidential candidate Michael) Dukakis. This was the real test for a Democrat.”

Yet he won’t criticise President George W. Bush: “I’m always at odds with my own constituency. I support every president. Period.”

That’s been Nicholson’s party line for years; he’d happily riff about the Lakers, free love, being stoned in the ’70s and such. But in public appearances and rare interviews, he avoided delving into the details of his personal politics. He now seems more at ease speaking about both his current sentiments and past ambitions.

“My political actor fantasies were never to be president, but rather to be Jim Farley or (Charles) ‘Bebe’ Rebozo or somebody like that who just kind of had a relationship” with the president, Nicholson said. “When he was at loggerheads, to be the ‘why’ guy, the alternative guy.”

Nicholson was last politically active during George McGovern’s 1972 campaign against Richard Nixon, and he points to his beliefs at that time in explaining why he left that realm of the public eye.

“I wanted to do solar energy. I wanted to legalise drugs versus the terrorist problem, which I was aware of in the ’70s. Because where else are they getting illegal money at that level?

“Enforce the monopoly laws of the Constitution they’re so proud of, which would have eliminated Enron and the interlocking directorate of conglomeration. Double teacher salaries. Find a way to liase from a personnel point of view between the military and the domestic police.

“These are all non-starters, what they call in politics. My position as a whippersnapper was hey, any of you people relate to any one of these issues, I’ll know you’re seriously interested in fundamental change. Until you do, I’m not interested in pie-baking contests.”

Rob Reiner, the director of Nicholson’s latest movie, The Bucket List, and a staunch Democrat, said he’d had many private discussions of politics over the years with the actor. “He’s outspoken when you get in discussions with him,” Reiner said, “but he’s never gone public with that.” Unless it has to do with the traffic lights at Mulholland Drive. On that topic, Reiner said, Nicholson “gave (LA) mayor (Antonio) Villaraigosa an earful the other night.”

And yes, it was indeed traffic lights that got Nicholson talking politics. At a top-floor Beverly Hilton hotel suite, he wore a comfortable dark Lacoste shirt and the mischievous grin that made him famous, poured himself coffee and munched on pieces of fruit.

“How do they talk about these small increments of energy conservation when we burn 60 per cent of the gas at stop signs and traffic lights?” he asked, eyes flashing.

From there, he was off: “Solar electricity is the only thing that can make an impact on the problem. It’s too big. We don’t have the ability to generate the electricity, to convert, unless we go solar. It’s an engineering problem, not a scientific problem.”

There is no momentum for solar electricity, he said, because of the powerful oil industry’s ability to set the scientific and political agenda. “There’s nobody in the field, no teachers, where their livelihood is not dependent in some way on petroleum grants. And I’m not vilifying the petroleum industry right now. Fact of the matter is, say there is an evil genius. Every day that whatever the petroleum interest is keeps this from being understood, that man is doing his job to the tune of whatever they make every day.”