California US Senate primary (2016)
Kamala Harris and Loretta Sanchez, both Democrats, finished first and second in the top-two primary for Barbara Boxer's open Senate seat. The November runoff was the first statewide federal race in California with no Republican on the ballot. Harris won with 62% in November.
Republicans were shut out of a major Senate race in the country's largest state for the first time in modern history.
The 2016 result confirmed that top-two could produce same-party runoffs and remove the GOP from statewide competition entirely.
The 2026 governor's race could produce the mirror image: a runoff with no Democrat on the ballot. The mechanism that excluded Republicans in 2016 can exclude Democrats in 2026 if the vote splits the other way.
