In the early 20th century many politicians were allowed to run under as many political parties in the primaries as they wanted. The future Chief Justice Earl Warren was a Republican but when he ran for Attorney General of California in 1938 he won the Republican ,Progressive and Democratic primaries so he had almost no opposition in the general election. When he ran for reelection as governor in 1946 he won the Republican and Democratic primaries and faced only token opposition in the general election from the Prohibition candidate.

(Book – Chief Justice – Ed Cray)