there were 3 or 4 games made around the last election – including the best known one – Dean for America – on http://www.persuasivegames.com
Ronny, the game that got the full release was ‘The Political Machine’ on http://www.stardock.com/products.asp (they also did ‘The Corporate Machine’)
Persuasive games sounds like a sub-branch of Serious Games (games for non-entertainment purposes)…and Omen’s quite right – it can be very difficult to get the fun into a non-entertainment game
One of the finlaists at this year’s Indie Games Jam at the Game Developers Choice Awards was a fun (and funny) game advocating vegetarianism