Knowland was the titular head of the California Republican Party from 1959 to 1967, when he passed the party leadership to the new governor, Ronald Reagan. In the 1966 California gubernatorial campaign, Reagan ran on a law-and-order message, while Knowland and his old California Republican rival Richard Nixon worked tirelessly behind the scenes, enabling Reagan to win two thirds of the primary vote over George Christopher, the moderate Republican former mayor of San Francisco. The momentum from Reagan's successful primary win carried over to the general election, where he defeated incumbent Democratic Governor Pat Brown in a landslide.