Heston's political activism had four stages. In the first stage, 1955–61, he endorsed Democratic candidates for president, and signed on to petitions and liberal political causes. From 1961 until 1972, the second stage, he continued to endorse Democratic candidates for president. Moving beyond Hollywood, he became nationally visible in 1963 in support of the Civil Rights Act of 1964. From 1965 until 1971, he served as the elected president of the Screen Actors Guild, and clashed with his liberal rival Ed Asner. In 1968, he used his "cowboy" persona to publicize gun control measures.