Although he was named by writer Martin Berkeley, he was investigated by the FBI as member of the Communist Party and was subpoenaed to appear before the House Committee on Un-American Activities. He testified on March 21, 1951 and was the first witness from Hollywood to invoke the Fifth Amendment objecting to being called to testify against himself. As a result he was listed in Red Channels and could find no more work in Hollywood and Broadway for one decade.
Between 1974 and 1977, he appeared in 26 episodes of the CBS Radio Mystery Theater.
Did voice-over links for serial episodes of the British cult Science Fiction series "Doctor Who" (1963), which were edited for American television (circa 1973).
Had a remarkably long career on the Broadway stage as an actor, director and playwright, working there from 1930-82. His most notable production was in the hit Rodgers & Hammerstein's musical, Oklahoma! originating the role of Jud Fry for 2212 performances.
Played Benjamin Franklin on Broadway in the original production of 1776, in the movie version of 1776 (1972) and in a National Park Service film presented in the 70s and 80s at Ben Franklin's home at Franklin Court, Philadelphia, Pennsylvania.
Played Jud Fry in the original 1943 stage production of Rodgers & Hammerstein's Oklahoma!.
Suffered a heart attack during the Broadway run of 1776 (1972), making him unable to attend the cast recording sessions. Understudy Rex Everhart took over the role and can be heard on the cast recording.
Twenty-five years after playing Wilson in The Great Gatsby (1949), he played the role of Meyer Wolfshein in The Great Gatsby (1974) .
Was nominated for Broadway's 1960 Tony Award as best supporting or featured actor in a musical for "Fiorello!".
Was the star of the historic Unit 891 production of Marc Blitzstein's "Camera Three: The Cradle Will Rock (#10.13)" (1964).