Last night I was thinking about the upcoming U.S. Senate election in California where centrist Dianne Feinstein recently lost the endorsement of California Democrats (they endorsed no one). I wondered what the chances were for a progressive candidate to upset her in November considering that we have a "top two" primary system (enacted Nov 2010) where two candidates advance irrespective of party.
That got me to thinking about the 2016 U.S. Senate election in California where Kamala Harris (D) defeated Loretta Sanchez (D) in the general after they both handily defeated all others in the primary (Duf Sundheim (R-who?) got 7.8% of the vote).
Well, in 2016, there was almost no reason for Republicans to turn out to vote in California since it was a foregone conclusion that Hillary Clinton would get our electoral votes and Donald Trump was rather unliked here so many abstained. I am sure that skewed the turnout statewide, as well as had a measurable impact on the national popular vote as we have one-ninth of the U.S. population. This may have played into Nate Silver's predictions if California was overweighted with respect to "plan to" voters in the polling.