They've managed to rig the election system in California to effectively shut out Republican candidates. It's rigged so that the primary usually produced to Democrap candidate, and you have to choose between them in the general election.
For my part, faced with a choice between two Democraps, if one is incumbent, I vote for the other.
It's pretty much become my default voting pattern any more; unless I have good reason to do otherwise, I always vote against the incumbent. I figure it's better to throw one crook out and get a new crook, than to let the same crook stay in.