'Stillwater': Matt Damon on the complexity of playing a Donald Trump supporter (exclusive)

Watch: Matt Damon discusses playing a Trump supporter in Stillwater

Matt Damon says he wasn't fazed about playing a Trump-supporting Republican in Stillwater and understands what drives people like his character to vote the way they do.

In the film, Jason Bourne star Damon portrays Bill — a roughneck working in the Oklahoma oil fields — who travels to Marseille in an attempt to clear the name of his daughter (Abigail Breslin), who is in prison for the murder of her partner.

During a loaded scene in the film, Bill is asked by a French character whether he voted for Donald Trump in 2016 and he responds that he didn't, but only because he was in prison.

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"Every time I do research and I have the chance to go and parachute into someone else's life for a little while, I always come back with the same lesson," Damon tells Yahoo Entertainment UK.

"The ways in which we're told we're different and the ways politicians will stoke those divides for their own self interest — what binds us and what connects us is so much greater than what divides us."

Damon — a prominent and outspoken Democrat — says he met people like Bill during his process of researching for the movie and came to understand why they decided to cast their ballots for Trump.

"Those guys don't agree with me politically, but you talk to them about it and they live in the reddest state in the union and they work in the oil fields. They vote Republican every time. It's not even a question," he says.

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The 50-year-old star adds: "When Bill is asked if he voted for Trump and he says no and they're kind of relieved, he says 'well, because I was in prison I couldn't'.

"It's kind of a naive question from them in the first place. His point is, of course, and these guys are totally unapologetic about it.

"They do one of the hardest jobs in the world, roughnecking, and they do it to provide for their families. The guys I talked to view it as a binary proposition. I'm either providing for my family or I'm not. I'm always going to choose providing for my family."

Damon says he thinks about characters like this "in the context of the piece" and assesses their relevance to the movie's message, rather than casting judgment on their politics and morality.

"You could play a completely morally bankrupt character, but the themes of the movie could be themes that align with your moral philosophy," he says.

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"I look more at the overall piece and what it's trying to say versus the character. The characters are just colours within the bigger painting and if your job is to be dark blue, then you're serving the bigger canvas."

Stillwater director Tom McCarthy says Damon's own personal politics were not a factor in the decision to cast him as Bill.

Watch: Tom McCarthy discusses casting Matt Damon as a Trump fan

"I feel like we've given politics too much credit in the last four or five years. Maybe that's because things have been so haywire in the world," McCarthy tells Yahoo.

The filmmaker adds: "I think really why I was casting someone like Matt is the kind of perception of Matt, specifically in movies, of being a man of really great character and moral authority and someone who was going to do the right thing more than often.

"We wanted to trade on that vision of the American hero a little bit and we wanted to subvert it somewhat."

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McCarthy points out that audiences have a pre-existing connection with Damon and so they will be inclined to spend their time "leaning into him and following him and believing what he says until that couldn't be the case any more".

He adds: "Early on in the writing, we started talking about who we need and we decided we needed an actor of Matt's not only calibre, but stature. Matt was our first choice, so it all worked out."

With the action split between Oklahoma and Marseille, Stillwater sees Bill bond with French woman Virginie (Camille Cottin) and her nine-year-old daughter Maya (Lilou Siauvaud).

McCarthy and his cast were able to premiere the movie on the big screen at the Cannes Film Festival thanks to the recent relaxation of COVID-19 restrictions.

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Damon says: "It's the first time for a lot of us that we were in a big group like that, all together with the lights off doing what we love doing — watching movies.

"I got emotional at the end. Like you I'm sure, I'm so freaking over this COVID thing. It just felt great to be out with people again."

Stillwater will be in UK cinemas from 6 August.

Watch: Trailer for Matt Damon drama Stillwater