I saw what happened to Bernie in 2016: There were three quarters of a million ballots which were thrown out.
So to make your life easy, if you want to vote in the Dem primary, sign up as Democrat. You can change it the next day. And in CA, since 2012 — and most people don’t realize this — we have same day registration. So if you do show up and your name is not on the voter rolls, please bring ID with you, a driver’s license, whatever photo ID you can find, anything, including something with your address on it like a cell phone bill. Cause if your name is missing, you can reregister on the actual voting day. Now, they made it very difficult to do that, and it’s still not easy, but they made it easier this time. You can say, well, if I’m not there, I want to register today. But why go through that? Register right now or check your registration right now.