Will Ferrell plays Cam Brady, a Democratic Congressman from North Carolina. He doesn't know much about being a congressman, nor does he care. But he loves being a politician. He cheats on his wife any chance he gets, and he knows that people love to hear certain buzz words, like 'Jesus' and 'freedom'.
When the corrupt Motch brothers (obviously based on the Koch brothers) decide Brady needs to be voted out, they convince Marty Huggins (Zach Galifianakis) to run against him. Marty is no match for Brady at first, but with the help of his campaign manager (Dylan McDermott), hired by the Motch brothers, he starts to lead in the poles.
This movie is pretty funny. Some of the jokes are obvious, and while the movie is a good satire of the political process, it doesn't tell us anything we don't know about politics (business has too much influence in politics, ect). Ferrell sounds like he's doing his George W. Bush impression, but without the squinty eyes and not quite as dumb. Galifianakis is doing a different character than we have seen before, and he is so innocent and well meaning that he has a real arc as he becomes more interested in winning than his family.
The best scenes in the movie involve the attack ads. Marty is accused of being an Al Qaeda terrorist (because he has a moustache), and Marty attacks Cam by revealing a "communist manifesto" that Cam wrote in 2nd grade. Marty gets Cam's son to reveal on camera that his dad is a horrible father, and Cam gets revenge on Marty by seducing Marty's wife.
I'm trying to remember the last thing Will Ferrell did that made me laugh as much as this movie. It would probably be his cameo in Wedding Crashers. And this is the best movie Galifianakis has done since The Hangover. It won't make my top 10 list for the year, but it's a very satisfying comedy.