Fern is correct, a New England urban Republican or Democrat is vastly different from a rural Southern candidate of the same party. Each area and state tends to have two major party choices similar to what it prefers to elect, so in that sense we already have some of the effect of a parliamentary system but with fixed alliances. Third party candidates tend to cater to those to whom neither party has appeal, which makes it quite difficult to get traction since both parties are concerned with appealing to 50.1% of the relevant voters. The big problem is that voters tend to pay attention to what politicians SAY they want to do rather than to what they HAVE done outside of election season.
So what if one wants something other a New England or Blue Dog Dem? I lived in MA, and the number of offices which had a "D" alone would be funny if it wasn't so tragic. Certainly there was considerable support for Dems, but there was a sense of resignation in that this is how it was, is and forever shall be. Now I'm sure this situation must exist with the parties reversed somewhere, but that's not the point. It's not who has the political monopoly but that one is allowed to exist to begin with.
As a people we have done a horrific job of understanding our own political system. There ought to be impressed on grade school students how things were originally meant to be for our nation, and a careful examination of where we succeed and fail and why. That needs to be a priority.
We tend to hold the opposition accountable, but circle up the wagons when it's our party.
No one ought to have a party. We ought to have values instead. That's not enough. We need to self examine and ask as honestly as we may why we think as we do, and if we are accepting something because it sounds good, and examine if it fulfills the expectation in fact. Drop the knee jerk "you are a X shill" and figure out if you know what you are talking about to begin with.
The Dems do it now with health care, and the Reps did it with Iraq, and there was never a choice between them.
Until we drop our own partisan attitudes and hold everyone equally accountable (and that includes ourselves in that we need to understand precisely what's at issue), we will forever be slaves. Slaves to partisan politics and our own ignorance, which controls us just as much as any chain.