In 1947, while many Hollywood figures were being blacklisted for similar activities, Peck signed a letter deploring a House Un-American Activities Committee investigation of alleged communists in the film industry. A life-long Democrat, Peck was suggested in 1970 as a possible Democratic candidate to run against Ronald Reagan for the office of California Governor. Although he later admitted that he had no interest in being a candidate himself for public office, Peck encouraged one of his sons, Carey Peck, to run for political office. He was defeated both times by slim margins in races in 1978 and 1980 against Republican U.S. Representative Bob Dornan, another former actor.