Al Franken loves to tell the story of how his dad would laugh at Buddy Hackett until he coughed up phlegm. Those evenings with his father, watching Johnny Carson in the living room of their Minnesota home, inspired Franken to become a comedian. Franken’s dad was also a card-carrying member of the NAACP who quit the Republican Party in 1964 because presidential nominee Barry Goldwater opposed civil rights.

So it’s no surprise that Franken does such a dead-on impression of Henry Kissinger, or that his Stuart Smalley character gave advice to the defeated Al Gore on Saturday Night Live. Nor is it a surprise that Franken has evolved from a political satirist into a political gadfly who’s mulling a run for Senate in 2008. For him, politics and comedy are deeply intertwined.

Al Franken: God Spoke, the latest documentary by Chris Hegedus and Nick Doob (makers of The War Room), follows the arc of Franken’s long, funny career. The film portrays him as a man passionately intent on making a difference in American politics, using his humor to sort out how. The feature-length documentary starts with the book tour for Lies and the Lying Liars Who Tell Them: A Fair and Balanced Look at the Right, which brings Franken face-to-face on stage with right-wing nemeses Bill O’Reilly and Ann Coulter. We then watch the rocky beginnings of the Air America radio network, the heartbreaking 2004 presidential race and Franken’s victory over Rush Limbaugh in talk radio ratings, with parenthetical clips from old SNL routines.

While the filmmakers unfortunately abandon the “God spoke” conceit almost immediately, there is a through line: Franken’s deep admiration for Paul Wellstone, the progressive senator from Minnesota whom Franken called a friend. Wellstone’s untimely death in a plane crash days before the 2002 election left a huge hole in the heart of the progressive movement; for Franken, it was personal.

If you’ve listened to Franken’s show on Air America, you know his obsession with fact checking the comments of Rush Limbaugh, Sean Hannity and his good buddy O’Reilly (who still hasn’t learned not to take Franken’s bait–here’s hoping he never will). As he tells an audience of high school students in the film, “What I do isn’t propaganda. I take what they say and use it against them. What I do is jujitsu.”

Footage of the show and of Franken backstage with his co-host Katherine Lanpher and his young writing team show Franken’s constant oscillation between funny and serious. When Franken’s out in the field, however, confrontations with right-wingers show Franken’s tenacity in a different light. While covering the Republican National Convention, the cameras catch RNC bouncers wearing Secret Service-style earpieces encircling Franken so as not to allow him to move around on the floor. And when Franken goes to a Newsweek party for RNC attendees as an invited guest, he’s clearly in enemy territory: William Safire and former Sen. Alan Simpson of Wyoming threaten to kick his ass. They may be kidding, but the animosity is real. Franken doesn’t fold: He does his Kissinger impression for Kissinger, and calls C. Boyden Gray an asshole for not picking up his dog’s poop.

After Kerry’s defeat, Franken gets more serious. He and his wife move back to Minnesota as he feels out whether he’d be a viable candidate to run against Norm Coleman and win back Wellstone’s Senate seat for the Dems. A representative from the United Steelworkers union asks, “How do you convince people that you don’t look at politics as a form of entertainment?” The answer is evident in every vintage SNL clip, and in the way Franken’s stories about comedy always come back around to his political ideals: To him, entertainment is a form of politics.

Franken will broadcast his Air America show live from UNC’s Carolina Union on Friday, April 7 from noon-3 p.m.