A first past the post system tends to having two parties. That's the way of things. The wiki article on it isn't bad:
http://en.wikipedia.org/wiki/First-past-the-post_votingAssuming there is an actual contest, a voter has every incentive to vote for one of the major parties.
So, this:
If you vote for either of the two big ones, it's your fault you get stuck with their shit. It's that simple.
is ridiculous and needlessly inflammatory. It's like blaming US voters for using dollar bills.
That being said, due to the way politics and voting works in America, as opposed to say Britain, elected officials tend to cultivate personal constituencies. And, b/c there is an overwhelming incentive as a politician to join one of the two major parties, the parties tend to be very big tents (although the Republican Party may have proven too small of one in certain key ways). Which is to say, a Republican (or Democrat) in one state may, and often do, vary quite a bit from a Republican (Democrat) in a different state or even a different district.
