California holds its non-partisan primary today. All candidates appear on a single ballot, with the top two vote-getters, regardless of party, moving on to the general election in November. We discussed some of the implications of that type of ballot in a short primary overview yesterday.
While this type of primary may yield some odd outcomes, such as a major party being shut out of a general election race, it also may prove to be a very good predictor of what to expect in November. Analyzing about 25 years of top-two results, the New York Times finds that "the California primary elections on Tuesday might give us a better idea of whether Democrats are headed for a so-called wave election — or whether their recent slide in the generic ballot and the bump in President Trump’s approval rating mean they should worry."
The data shows that "Since 1990, the major party vote share in top-two congressional primaries in Washington (which also uses the top-two system) and California has differed from the general election result by an average of just three percentage points."