In an MIT lecture on The Financial Crisis, the Recession, and the American Political Economy, Charles Ferguson, author of the documentary Inside Job, describes the U.S. political system as follows:
•The two parties have formed a duopoly in which both parties have agreed to agree on money issues and to disagree on social issues.
•Both parties serve the financial sector and the wealthy. Thus they agree on (de-regulation) / (non-)enforcement / (no )criminal prosecution for the financial sector, as well as on antitrust, campaign financing and tax policies.
•Both parties agree to retain their base through conflict over social policy: Religion, education, evolution/creationism, gay rights, abortion, environment, war, terrorism.
•The sustainability of the duopoly depends upon barriers to entry against newcomers via ballot qualification, redistricting/gerrymendering, campaign and advertisement costs, lack of parliamentary system and lack of ranked-order voting.
While I agree on this 'duopoly' description, Ferguson has a few points wrong.
War and terrorism are no longer social issues but are about money making as well as about keeping potential competitors away from the system. Therefore both parties agree on keeping the wars going and on keeping the terrorism bogeyman alive...
http://www.moonofalabama.org/