I don’t know what Cagney’s politics were.
Now I do remember reading the story where Humphrey Bogart, his wife, Lauren Bacall and others went to D.C. to protest the House UnAmerican Committee, not sure of that date, late 1940’s very early 1950’s.
Cagney was an FDR Dem in the 1930s, but was quite conservative later in life. Seemed to follow a similar path that Reagan did.
An interesting read with a lot of surprising information.