http://www.particracy.net/ - Particracy is a political simulation game where the player takes on the role of a political party in a fictional nation. Players propose and vote on legislation, form cabinets, determine economic policy and join international treaties as they compete for votes with other political parties in their nation. The opinions of voters in each nation is measured on a wide variety of opinions, meaning every region and every nation is unique, and constantly changing. Will your nation be a free market paradise or a socialist utopia? Only the voters will decide.
http://www.democracygame.com/ - Democracy is a detailed simulation game that is 'turn based' where each turn of the game represents 3 months of time. Elections are held every 4 years. The game has a complex internal model to represent the population of your country. A large number of different 'voter groups' are modeled, such as Motorists, Trade-Unionists, Unemployed people, Wealthy people etc. The simulation allows people to be in several groups at once, so for example, an unemployed poor motorist will be influenced by the opinions of all 3 groups when it comes to election day.
http://www.senateseeker.com/ - Senate Seeker is an online simulation game based on American politics. It allows players to run House, Senate, Governor, and Presidential races. If you win your campaign to either of these posts, you gain the power to write and pass laws within the game, vote on Supreme Court of the United States (SCOTUS) nominees and, in general, run the government of Senate Seeker.
http://www.votersmind.com/ - Voter's Mind is a game which centres around the imaginary nation of Aurelia and elections for the Senate, House of Representatives and President. The game is based around forums
Hope this is somewhere to start.