Political movies are a tiny genre. They're so rare they're barely a genre at all. Most people don't care enough about politics to go see them and you'll lose half of those who do if you make any political point whatsoever. Studios treat politics like smallpox. Directors know they do. And actors are unwilling to lose half their fan base by sticking their colours to the political mast.
So the emergence of a film like Grassroots is surprising and welcome. This charming indie movie, directed by Stephen Syllenhaal and starring American Pie star Jason Biggs, follows the attempt of green campaigner Grant Cogswell to get on the Seattle city council. It wears its left-wing politics on its sleeve and turns the tried-and-tested 'idealistic good guy vs corrupt bad guy' narrative on its head, by showing considerable sympathy for the Democrat incumbent Cogswell is trying to unseat, while all the while encouraging you to vote for its protagonist. It's a political film for grown-ups, with the heart of a student activist.
While the script may be smart, the decision to make an explicitly left-leaning film in America is fraught with potential pitfalls. I mention this to Biggs and Syllenhaal when I meet them in the incongruously upmarket surroundings of a top-floor suite in the Mayfair hotel. Left-wingers talking about their principles in a posh hotel sounds like the butt of countless right-wing jokes, but the two men are thoughtful and circumspect about the decision to make the film. Biggs in particular has a lot to lose. He could alienate his fan base from American Pie by making a film with a political slant.
"I did write some anti-Republican tweets recently and it got me in a bit of a mess," he admits. "The far-right in America - a small, very vocal group of them - came after me and I was like: 'Oh shit, I'm just making jokes'.
"In Hollywood you feel very protected in left-leaning world. Then you mention something which indicates your leanings and all of a sudden your Twitter timeline gets blown up with hatred. You realise 75% of America - people who love you, who go see your movies - now don't love you because you support Barack Obama."
For Biggs, who is a surprisingly imposing presence given the self-deprecating nature of the characters he plays on screen, the risk of a political film was outweighed by the chance to escape his American Pie persona.
"The truth is when you do a movie like American Pie, then three sequels, you become identified as one character, which is a by-product of its success," he says. "When you get an opportunity like Grassroots, when a filmmaker like Stephen actually says 'I believe there's a side to you that's a lot more complex, subtle and darker', you jump at that opportunity."
Whatever Syllenhaal saw in Biggs, it worked. He plays an election manager fighting to get Cogswell elected. In a badly-fitting suit and cheap glasses, he looks the part, and his mix of caustic asides and political in-jokes help give the film pace and wit.
Leaning back on the plush sofas of the suite, Syllenhaal seems exhausted by the process but still excited by the film he's made. You can tell it's his personal baby. He got it financed almost exclusively by people in Seattle, went without the perks of his usual TV work and even held political debates around America when the film premiered.
"It’s hard," he says. "We made it in a grassroots way. We really made it from a wing and a prayer. I slept on couches in the beginning. I was making this movie and I was making it for nothing if I had to."
Syllenhaal is softly-voiced and relaxed. It’s hard to imagine him barking orders on set. His calm, moderate tone is part of the DNA of the film. While honest about its principles, it goes out of its way to humanise people on all sides of the story. "I don't want to demonise the conservatives, you know," he says. "The film is complex and it isn't like I'm beating people over the head with a liberal cause. I can sometimes do that," he says, smirking, "but not in the movies. I don't ever want to do it in a movie."
True to his word, the film has a complex message about idealism and realpolitik. Neither option comes out of it well. Syllenhaal clearly considers realpolitik to be a euphemism for corporate interests and the status quo, but he's acutely aware of how idealism can lead people to become puritanical and cruel. His idealistic protagonist, for instance, is deeply flawed, and the 'villain' of the piece becomes increasingly sympathetic as the film progresses.
"Idealism is critical," he says. "Cynicism is a false approach. It's a delusional strategy for not getting hurt. Idealism is terrific, but then you have to become realistic - you have to negotiate. It's one thing to get elected, the other is to govern. And governing is vastly harder."
I suggest that by refusing to demonise the incumbent, Syllenhaal isn’t just challenging our beliefs around politics but also the traditional structure of a Hollywood screenplay, which usually coerces viewers into an emotional response by ramping up the evil of the villain. "I've got to make a living, but ultimately I'm doing this to stir the pot," he responds. "I want to cause trouble. There aren't any real demon human beings. Generally, people who are incumbents aren't horrible people."
The film enters difficult territory when we realise our two white protagonists are trying to throw out the only black member of the city council. One character even suggests their groundswell of support is a result of barely-concealed racism. It's a uniquely uncomfortable moment in the film and one only a mature script would dare address.
"There is a tension between the two white slacker dudes who are trying to defeat the only African-American city councilman," Syllenhaal says. "So it's like: 'where is this going? Take Rocky, which in a way is a model for it, in which there's the black champion and there's the white Rocky. A great movie - and I'm not saying this is a great movie - but the great movies set up, somewhere along the line, a moment for the audience to go: 'Oh shit, we have a filmmaker who is out of control and we don't quite know where this is going to go'."
The film was released in the US during the build-up to the election campaign, with Syllenhaal making some rather hopeful statements about his desire to affect the race. We can presume the effect was minimal. In the UK, it's being released after the election, in the hope the surrounding coverage helps boost its audience. With the Republicans heading further away from the centre in a bid to placate angry tea-party activists, are Syllenhaal and Biggs worried about the direction the right in America is taking?
"Yeah, man," Biggs says, as he bursts out laughing. "Are you kidding? I was really scared at the last election but then [Sarah] Palin essentially won the election for the Democratic party. But eventually a Palin will get elected. That's my fear."
Syllenhaal is more relaxed. He toys with the idea the heated temperature of debate on the American right may be exaggerated. "I'm a progressive and I'm generally frustrated with the way progressives don't seem to be willing to fight hardcore the way the right-wing is prepared to fight," he says. "And yeah, the right-wing is angry. But anger is news. It's not as angry by any stretch of the imagination as it appears from across the pond."
Speaking of across the pond, I'm intrigued by the pair's assessment of the UK political scene. Biggs made the rookie error of watching lengthy passages of the Tory party conference. He was particularly taken by a video of the prime minister and his wife going for a curry on his birthday, which attracted mockery online for its obviously staged qualities.
"Cameron just seems like a lunatic," he says. "I saw that horribly contrived video of him walking down the street in Birmingham with his wife. It was like: 'Oops, the cameras just caught us, we're going for a date'. Are you kidding me? There's fucking bodyguards. Is there a person in the UK who believes this?"
Boris Johnson, who made something of a name for himself when he went across the Atlantic to promote his new book this summer, gets a much better response. "He did all the shows and Letterman. He was incredibly likeable. Well, I think you know that. There's something about him. He's got this kind of shlubby…. He's got a thing. If I voted Tory, I would vote for him. Is he really a prime minister-type leader? I don't know, but it seems to me he's doing a good job with London."
I raise a sceptical eyebrow, but it's clear Boris' charm offensive works on either side of the Atlantic, and possibly further afield. Neither Biggs nor Syllenhaal will be too bothered. They have managed to make a political film, against all the odds, with the guts to treat its subject matter intelligently. Their work here is done.