information:classification
Political views

Like his father, Cooper was a conservative Republican; he voted for Calvin Coolidge in 1924 and Herbert Hoover in 1928 and 1932, and campaigned for Wendell Willkie in 1940. When Franklin D. Roosevelt ran for an unprecedented fourth presidential term in 1944, Cooper campaigned for Thomas E. Dewey and criticized Roosevelt for being dishonest and adopting "foreign" ideas. In a radio address he had paid for himself just before the election, Cooper said, "I disagree with the New Deal belief that the America all of us love is old and worn-out and finished – and has to borrow foreign notions that don't even seem to work any too well where they come from... Our country is a young country that just has to make up its mind to be itself again." He also attended a Republican rally at the Los Angeles Memorial Coliseum that drew 93,000 Dewey supporters. In 1952, Cooper, along with John Wayne, Adolphe Menjou and Glenn Ford, supported Robert A. Taft over Dwight D. Eisenhower in the Republican primaries.

Cooper was one of the founding members of the Motion Picture Alliance for the Preservation of American Ideals, a conservative organization dedicated, according to its statement of principles, to preserving the "American way of life" and opposing communism and fascism. The organization (members included Walter Brennan, Laraine Day, Walt Disney, Clark Gable, Hedda Hopper, Ronald Reagan, Barbara Stanwyck, and John Wayne) advised the United States Congress to investigate communist influence in the motion-picture industry. On October 23, 1947, Cooper was subpoenaed to appear before the House Un-American Activities Committee (HUAC) and was asked if he had observed any "communistic influence" in Hollywood.

Cooper recounted statements he had heard suggesting the Constitution was out of date and that Congress was an unnecessary institution, comments which Cooper said he found to be "very un-American", and testified that he had rejected several scripts because he thought they were "tinged with communist ideas". Unlike some other witnesses, Cooper did not name any individuals or scripts.

In 1951, while making High Noon, Cooper befriended the film's screenwriter, Carl Foreman, who had been a member of the Communist Party. When Foreman was subpoenaed by the HUAC, Cooper put his career on the line to defend Foreman. When John Wayne and others threatened Cooper with blacklisting himself and the loss of his passport if he did not walk off the film, Cooper gave a statement to the press in support of Foreman, calling him "the finest kind of American". When producer Stanley Kramer removed Foreman's name as screenwriter, Cooper and director Fred Zinnemann threatened to walk off the film if Foreman's name were not restored. Foreman later said that of all his friends and allies and colleagues in Hollywood, "Cooper was the only big one who tried to help. The only one." Cooper even offered to testify in Foreman's behalf before the committee, but character witnesses were not allowed. Foreman always sent future scripts to Cooper for first refusal, including The Bridge on the River Kwai, The Key, and The Guns of Navarone. Cooper had to turn them down because of his age.