“Swing Vote” is yet another hosanna to Americana, like 1997’s “The Postman” directed by Kevin Costner. Once again, Costner stars as a downscale everyman who upgrades to the great helmsman. Here he plays Bud, an alcoholic single dad laid off from his job at an egg packaging plant in New Mexico. Due to an accidentally unplugged voting machine, a vote in his name did count. And the outcome of the presidential election is undecided until he recasts his vote in ten days, the time frame of the screenplay by Joshua Michael Stern & Jason Richman. Joshua Michael Stern directs an ensemble cast stocked with news personalities, including Campbell Brown, James Carville, Mary Hart, Arianna Huffington, Bill Maher and Chris Matthews. The Republican incumbent (Kelsey Grammer) and the Democratic candidate (Dennis Hopper) come to town to woo the ultimate swing-voter. Tom Petty and Willie Nelson make cameos at the behest of the two contenders. The two campaign managers, played by Nathan Lane and Stanley Tucci, are stock types, but their quickie campaign ads to appeal to Bud’s supposed issues are brilliantly cynical. There’s scant political context in this public-service announcement: JFK is the most recent president mentioned, and there’s no trace of 9/11, Iraq or Afghanistan. “If America has a true enemy, I guess it’s me,” Bud confesses on national TV, when acknowledging a dereliction of civic duty. Madeline Carroll plays Bud’s take-charge 12-year-old daughter Molly, the single most wise, decent, competent, empowered character in the entire film. With a better wardrobe, she’d be a candidate for an American Girl doll. With Paula Patton, Judge Reinhold, George Lopez and Mare Winningham. 119m. (Bill Stamets)