Chotiner initially registered to vote as a Democrat, but soon switched parties, joining the Republicans. He involved himself in Republican politics, working on Herbert Hoover's unsuccessful presidential re-election campaign in 1932. In 1938, the young attorney ran against longtime Republican incumbent Charles W. Lyon for the California State Assembly. Lyon cross-filed and secured his re-election by winning both primaries, defeating Chotiner in the Republican poll, and narrowly beating Robert A. Heinlein (who subsequently turned to writing science fiction) in the Democratic contest.