Cronk was elected to the Los Angeles City Council District 5 seat in 1945, succeeding Ira J. McDonald, who had quit the post to run unsuccessfully for mayor. Cronk was endorsed by the conservative American Federation of Labor in that race, whereas the rival and more liberal Congress of Industrial Organizations went for Robert J. Kennedy. Cronk was reelected in the primary votes of 1945 through 1951 but did not run in 1953. Instead, he took on the job of campaign manager for Norris Poulson, who was successful in ousting Mayor Fletcher Bowron that year.