The Tea Party is a protest movement and hence, at its core, it is about being angry. Who or what they are angry at is less clear, but it is clear that it is "they" not "us". "They" might be people of a different race, and often are, but not exclusively. "They" might also be gays or liberals changing the way things used to be. "They" are very often immigrants, as they are a very easy target. "They" are often those who are perceived as the "cultural elite".
Similarly, on the protest wing of the left, "they" are the "economic elite" or the "bigots".
Generally speaking, protest movements are usually, but not always, bad news for democracy. Because they are usually more about being against something which is rarely clearly understood, rather than actually being for anything. The protest movements that are beneficial for society are those that fight for something, usually for equal rights for groups who are being discriminated against.
Pragmatic Progressivism is and has always been the best way to proceed. Listen to Obama. I currently think there is very good reason to fear that the democrats will go the way of the republicans and succumb to populism.
Populist Rhetoric, is good if used in the appropriate way.
