Assumptions

Jungle Primary

California has a top two primary system where the top two vote getters regardless of party advance to the general election.

Gerrymandering is real.

The majority of districts in California are designed to be 60% to 40% for the incumbent’s party in the primary and 55% to 45% for the incumbent’s party in the general election

Party Identity is important.

People are busy and they do not have time or inclination to read and understand individual candidate’s specific policy positions. It probably shouldn’t be this way, but after a 10 hour shift and a 2 hour commute it is hard to blame people.

Districts don’t change party.

Because the districts are drawn to be safe, and individual policies are unlike to make a difference, it is unlikely for a non-incumbent party member to unseat an incumbent. Even if that incumbent is unpopular.

What Does This Mean

What is the most likely outcome given these assumptions.

If an incumbent faces a member of the opposite party in the general the incumbent wins.

If an incumbent faces a member of the same party and members of the opposite party in the primary, the incumbent wins. The opposite party members get 40% of the vote and the incumbent party members split the remaining 60% the majority going to the incumbent due to institutional inertia.

If an incumbent faces a member of the same party in the primary without members of the opposite party, the incumbent loses. The incumbent and the challenger split the 60% and the challenger gets the votes of the opposition party as well.