I had no idea!
From Wikpedia:
“McQueen was conservative in his political views and often backed the Republican Party. He supported the Vietnam War, was one of the few Hollywood stars who refused numerous requests to back Presidential hopeful Robert Kennedy in 1968, and turned down the chance to participate in the 1963 March on Washington. When McQueen heard a rumor that he had been added to Nixon’s Enemies List, he responded by immediately flying a giant American flag outside his house. Reportedly, his wife Ali McGraw responded to the whole affair by saying, “But you’re the most patriotic person I know.””