|I was skeptical. That's not a phenomenon that I'd ever heard before. If it's true, is it unique to California?
I looked at two different metrics. I compared the votes for Republicans and Democrats in races where the race was within 60%-40% in November, as we're looking at how close races go.
What I found surprised me. If you move over to the right you can see that the Republican vote share dropped by:
Some of this was that independents have never shown up for primaries. Still Democrats went up:
It's difficult to say this phenomenon is due to anything in particular. 2010 was a Republican year with competitive Republican races. 2008 was a Democratic year without competitive Republican races.
I looked at actual turn-out. Unfortunately the SoS only keeps track of turn-out for the primary. So looked at exit polls. The Democratic advantage increased by:
These are statewide numbers and 2010 stands out a bit. That may have been due to the competitive Republican statewide elections.
I think it's safe to make the conclusion that in the past Republicans had elevated turn-out in primaries. Could it be different this year?
Yes. Top two will definitely mean higher turnout from DTS voters. If DTS voters lean left then that would lessen the difference between the primary and general election.
There's no reason for Democrats not to turn out in competitive top two elections. Of course I'm not sure it's that much more compelling than the old system. Jerry McNerney has no other Democrat in the race. He advances even with low turn-out.
On the other hand, low Democratic turn-out in a CA-26, CA-31, or CA-52 could result in two Republicans advancing. The downside of low turn-out could be a disaster this year.
I'll want to wait until I see the party breakdown of turn-out before making a final judgement but I can't see any reason to think that Democrats won't add several points from June to November.