"they might actually be willing to work together"
If politicians had valid incentives for working together and serving the interests of the American people at large, I am sure they would. Unfortunately, the political system and nature of the political discourse means that the ruling class (er, I mean politicans) act in their own interest, and can get away with it.
This has been the state of affairs for almost a hundred years. The only thing that makes me somewhat optimistic is that a growing majority of people have realized that government is not always working in their best interest (unlike people in previous decades) though sadly many still cling to a partisan read of government affairs.
eg. "Oh, but the nice proggies and dems aren't really like that!! It's the rethuglicans fault that Obama can't stop the police state, close guantanamo, end the wars, or cut the military budget!!"
-or-
"The socialists are the one's ruining America!! The stimulus is Obama's fault, and once we get rid of the evil Dems all will be right in America again!!"
Both of these points of view are dangerously ignorant of the reality of the situation. The two political parties are both dangerously illiberal, statist, militaristic, corporatist, and believe that they have a moral authority over the American populace. Everything else is just window dressing.
It is a big cliche to say that the two parties are the same, but it's a cliche because it's true.
Thus, even if a 'tea party' candidate is a loon, a little racist (looking at you Rand), and isn't intimately familiar with the channels of power or influence (a good thing) I still view them as a vastly superior choice to whatever piece of filth is churned out by the Republican or Democratic party machines.
Anyone who wants government to enforce, to build, and to control less than it currently does is always a better candidate.
The main danger of course, and the reason that no third party has ever existed for long in America, is that the nature of the political system edges out anyone who comes in third. If nothing changes, groups like the tea party will either be subsumed by the Republicans, or replace and become them, with all of the hypocrtical trappings that go with the modern right.