According to the LA Times, there's no middle ground, leaving an opening for a new third party to rise. Why do I find this familiar?
The Times is an Ultra Liberal supporter of the Democrats. Do you think that this just MIGHT have an impact on this type of story?
And, the politician they cite is in one of the most liberal counties in the State (home of University of California-Santa Cruz, which is even more left wing that Cal Berkeley). Running as a Republican is political suicide in that country.