The two party system is pretty much institutionalized. Our electoral system makes it very difficult to get on the ballot without broad support or a ton of money. The parties have their tendrils in everything, business, unions, news media. Yes, there is a Green Party, and others, but they aren't invited to debates, or given the time of day. It's a democracy, you see. EDIT: I do have hope for Americans Elect though. They are getting the support and delegates to have an independent candidate that is nominated by a popular vote put on the 2012 ballot.
Voters need to hear pragmatism. IMHO the Green Party is more about 'everything that has gone wrong', rather than interesting solutions to problems. But, I guess the GOP is there too now, with the Dems close behind.