For over a year now progressives have wondered how Donald Trump managed to get himself elected president.

The answer may be found in the documentary Get Me Roger Stone, directed by the trio of Morgan Pehme, Daniel DiMauro and Dylan Bank, a Netflix release that has qualified for Oscar consideration. It reveals how Stone—the gleefully Machiavellian GOP operative and master of the dirty trick—more than anyone else orchestrated Trump’s political rise.

“Roger first hatched this idea back in 1987 of Trump running for president and then spent the next 29 years cultivating that seed so that it would finally grow into the presidency,” Pehme tells Deadline. “Not only was he trying to grow Trump the candidate, but he was also working to degrade our politics in a way that would make us more vulnerable to a Trump presidency. That’s one of Roger’s real gifts is that he sees the soft spots in our politics and he sees how to exploit them to maximum effect.”

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That ability was put to early use for President Nixon’s re-election campaign in 1972, when Stone was just 19 (he famously sports a Nixon tattoo on his back). Over decades, he developed a gift for exploiting opposition research, often to the point of blurring ethical lines — and he did it with gusto.

“So many people practice the dark arts in politics, but they try to paper over their misdeeds and make these saccharine attempts at doing good. Not Roger. He was only too happy to revel in infamy,” Pehme says.

It was after working on Ronald Reagan’s White House campaigns in 1980 and ’84 that Stone first hooked up with Trump. The filmmakers say another notorious Republican political insider—Sen. Joseph McCarthy’s former chief counsel Roy Cohn—put them together.

“Cohn introduced Trump and Roger and saw in them kindred spirits,” Pehme maintains. “Certainly a match made in heaven, or hell, depending [on] your perspective. Roger quickly became one of the closest people to Trump.”

As Trump was busy in New York building his real estate empire and his media profile, Stone did lobbying work for him in Washington. In the film, Stone describes early on regarding Trump as a “prime piece of political horseflesh,” and he tried several times saddling him up for a presidential run.

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But it wasn’t until after President Obama got into office that Trump seemed to get truly serious about the idea. Trump rode to prominence as a political figure largely by pushing the false claim that Obama wasn’t born in the United States. The film strongly suggests it was Stone who guided Trump in making hay out of the “birther” movement.

His tactical advice went well beyond birtherism, the filmmakers believe. They make a case for Trump adhering closely to a set of political principles championed by Stone.

DiMauro says they include these maxims: “‘Attack, attack, attack, never defend.’ ‘It’s better to be infamous than never to be famous at all.’ ‘Hate is a more powerful motivator than love.’ And I think Trump embodies all of these rules—Stone’s Rules.”

For Trump’s 2016 run, Stone played a key advisory role and helped rally the group that would be vital to the candidate’s White House win—angry, white working-class voters.

Stone’s role in an episode that damaged Hillary Clinton’s campaign is the subject of dispute—the release of hacked emails from the Democratic National Committee and Clinton’s campaign chief John Podesta. Stone has acknowledged contacting “Guccifer 2.0,” the suspected Russian entity that did the hacking, but denies serving as an intermediary to Wikileaks, which published the emails.

The directors interviewed Trump for their film, shortly before he announced his candidacy for president. Trump spoke on camera, admiring Stone’s toughness—but he apparently held reservations about the motives of the filmmakers, who acknowledge being on the left of the political spectrum.

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He did call Roger right after we interviewed him and said, ‘You know, these guys are a bunch of liberals. I don’t think they have your best interests at heart. You really shouldn’t do this documentary with them. It’s going to be a hit piece,’” DiMauro says. “Roger told us that.”

DiMauro describes what he calls an “odd” moment during the interview with Trump when the latter stumbled over a couple of responses to questions. He says Trump paused to tell a person in another room to quiet down.

“There was no one in the other room. He was yelling at an imaginary person, blaming them for making noise for [his] misspeaking,” DiMauro recalls. “We think it’s representative of what kind of person Trump really is inside. He’s someone who could never admit a mistake and has to blame someone else for some sort of failure.”

As to what kind of person Stone is, the directors pull no punches.

“He’s absolutely vile and he disgusts us in so many ways,” DiMauro insists. “At the same time, it’s extremely fascinating to have a political conversation with him, although you might want to pull your hair out [afterward].”

Stone himself appears to have harbored no reservations about participating in the film, perhaps operating under his rule that it’s better to be talked about than ignored. And he’s even given a full-throated endorsement of Get Me Roger Stone, the filmmakers say.

DiMauro states, “He called the film ‘the greatest political documentary of all time. It’s a masterpiece. The main character, of course, is very handsome, and has great suits.’”