With so many Democrats running, the party’s fear is that the vote will be splintered, allowing Republicans — who have fewer candidates — to dominate some primaries. The party and allied groups are spending more than $4 million on just three campaigns, intervening in one contest to prop up a favored candidate; attacking a Republican from the right in another; and even reminding people not to waste their votes on “ghost candidates” who have dropped out yet remain on the ballot.

As any progressive activist will explain through gnashed teeth, the head-snapping scramble is because of the state’s “top two” open primary system, which allows the two leading vote-getters — regardless of political parties — to advance to the general election.

The “top two” system was meant to create incentives for political moderation in a state where about a quarter of the voters are independents, but it has created immense stakes for Democrats: They need to win 23 seats to take back the House, and party officials believe the path runs through the seven competitive California districts, all of which Hillary Clinton carried in 2016.