The Dems to a man, pick people ideologically in lock step with them. They advocate as a solid block.
The Reps to a man, pick people ideologically in lock step with the Dems. They advocate as a solid block.
Stragglers? Only a select few...
And the "stragglers (I'm assuming they're actual conservatives) advocate on personal hot-button items and have no sense of solidarity no matter what the consequences. When a Palin supports a candidate in a race, if there are any perceived hot-button flaws, folks point out how she may not be the real deal instead of analyzing why she would offer the support. Can't win even a little bit with that sort of fragmentation.