Lewis kept a low political profile for many years, having taken advice reportedly given to him by President John F. Kennedy, who told him "Don't get into anything political. Don't do that because they will usurp your energy". Nevertheless, he campaigned and performed on behalf of both JFK and Robert F. Kennedy. Lewis was a supporter of the Civil Rights Movement. For his 1957 NBC special, Lewis held his ground when southern affiliates objected to his stated friendship with Sammy Davis Jr. In a 1971 "Movie Mirror" magazine article, Lewis came out against the Vietnam War, when his son Gary returned from service traumatized. He vowed to leave the country rather than send another of his sons.