In the first primary in December 1963, McKeithen faced a wide array of intraparty opponents, including former Governor Robert Kennon, segregationist Education Superintendent Shelby M. Jackson, and the Ku Klux Klan wizard Addison Roswell Thompson, a taxicab operator from New Orleans.
McKeithen, with Earl Long's widow, Blanche Long as his campaign manager, fought to win the backing of the still-influential 'Longite' forces.