You might give Neil Postman's "How to Watch the TV News" a shot. He had some very prescient points regarding media and how it has transformed politics. Chomsky also has some interesting points on partisan politics.

But yeah, I totally agree, it just seems like very narrow minded allegiance. I think in the US it has a lot to do with conflicting interests of people in high-density places and the rural. I've got a population map overlayed on election results right now, and the data seems to fit that conclusion.

"We" are all held, arbitrarily, in the same group, which is... Absurd. It's like a hostage situation and it seems nobody has recognized that we're being held involuntarily.