Over the years, Sundance has been famously friendly to eco-themed docs, providing high-profile premieres for films such as “An Inconvenient Truth” and “The Cove,” as well as political hot potatoes like “Why We Fight” and “8: The Mormon Proposition” (about gay marriage). Among fests, Sundance is hardly alone in offering a platform to left-leaning docs. Michael Moore’s “Fahrenheit 9/11” won the Palme d’Or at Cannes, while Alex Gibney’s “Taxi to the Dark Side” is just one of many lefty Tribeca offerings.

By contrast, “2016: Obama’s America” co-directors Dinesh D’Souza and John Sullivan avoided the U.S. fest circuit altogether in favor of tapping into their own constituency — and it doesn’t seem to have hurt the film in the slightest. A politically conservative adaptation of the anti-Obama book, “2016” earned more than $33 million, making it the second-highest-grossing political doc after “Fahrenheit 9/11.”

For most nonfiction pics, however, the fest circuit is a vital component of a film’s life cycle, which is why businessman-turned-documaker Dennis Michael Lynch submitted his film “They Come to America” to nearly 30 U.S. festivals, including Sundance, Tribeca and Silverdocs, to no avail. He contends the film was rejected by programmers around the country on the basis of his conservative stance on immigration, as opposed to the film’s quality. Lynch went on to self-distribute and decided not to “waste a dime on festivals” when it came to the release of ‘They Come to America II.’ ”

(Lynch’s film did play in the documentary competition category at the 7th annual Myrtle Beach International Film Festival in April 2012. Fest’s founder and director Jerry Dalton said that Lynch did not show up for his own screening in favor of a game of golf. According to Dalton, when he asked Lynch if he could play “They Come to America” at film festivals in Michigan, the helmer refused.)

On the other hand, the cinema verite-style “Caucus,” about the 2012 Iowa Republican caucus, was accepted into such established fests as HotDocs and AFI Docs last year, although helmer A.J. Schnack admits it was a hard sell.

“It’s no secret that in terms of documentaries, film festivals tend to skew more toward liberal or progressive subjects,” Schnack says. “I had one (programmer) tell me they couldn’t stand the sight of the people in (‘Caucus’). I took them at their word that that was why they weren’t screening the film. I’m sure that’s not the only case where that happened.”

That doesn’t mean conservative or right-leaning docs aren’t welcome at top-tier festivals. This year, Sundance will premiere Greg Whiteley’s “Mitt,” a behind-the-scenes look at Mitt Romney’s presidential bid, and last year, Robert Stone’s pro-nuclear power pic “Pandora’s Promise” and R.J. Cutler’s “The World According to Dick Cheney” both debuted in Park City.

“We are politically agnostic in the way that we look at films,” says Sundance senior programmer Caroline Libresco. “We never approach the programming process with any kind of pre-determined notion of what we want the films to say or the political point of view of the film. What we are looking for is great storytelling that explores complex issues and provokes thinking about those complex issues.”

Toronto programmer Thom Powers agrees, but adds he receives “very few” right-leaning docu submissions. “I actually get a lot more of what I describe as left-wing propaganda films.” Last year, Powers brought Errol Morris’ “The Unknown Known,” about former defense secretary Donald Rumsfeld to TIFF and says the atmosphere verged on contentious. “Audiences came with the expectation of wanting to see (Rumsfeld) pilloried and anything short of that happening in the film leaves them unsatisfied,” Powers says. “It’s unfortunate for the audience to set that kind of standard because they wind up missing the other things the films have to offer.”

But Whiteley says he isn’t worried about the Sundance reception of “Mitt,” which was recently acquired by Netflix.

“I’m a bit more concerned about conservatives (seeing the film),” Whiteley says. “If you are somebody who was an ardent Mitt Romney supporter, maybe you are hoping this film demonstrates why he should have been president, but this film doesn’t go into that at all. I feel like Romney could have been a Democrat — it really wouldn’t change how the film plays.”

But will the fact that Whiteley is a member of the Mormon church hurt him in the same way religion hurt Steve Hoover’s doc “Blood Brother”? The film, about American Rocky Braat’s work on behalf of an AIDS-afflicted community in India, won both the Sundance audience and grand jury awards last year, but was later criticized by journalist Tom Roston, who implied that Hoover manipulated audiences by not revealing a personal tie with an evangelical church.

The film failed to garner a major distributor or a spot on the Academy’s shortlist despite glowing reviews and a tradition of Sundance winners going on to Oscar glory.

In an open letter on the film’s website, Hoover called the claims “troubling”: “Neither Rocky nor myself consider ourselves evangelicals. We are both Christians, but we have no interest in pushing intolerant political agendas or using legislation to enforce doctrine. Nor do I see filmmaking as a means to fill the pews or make converts. I had no secret agenda.”

In Libresco’s experience, the motivation to make docs tends to originate from the progressive side of the aisle.

“I’ve noticed that the large majority of (nonfiction films) tend to be galvanized and motivated by an interest in a complex view of the world and in perhaps disrupting the status quo.”