Johnson took office on November 22, 1963, following the assassination of his predecessor, John F. Kennedy. He easily defeated a primary challenge by segregationist Governor George Wallace of Alabama to win the nomination to a full term. At the 1964 Democratic National Convention, Johnson also won the nomination of his preferred running mate, Senator Hubert Humphrey of Minnesota. Senator Barry Goldwater of Arizona, a leader of his party's conservative faction, defeated liberal Governor Nelson Rockefeller of New York and Governor William Scranton of Pennsylvania at the 1964 Republican National Convention.