In 1964, he was elected as a Republican to the Senate, having defeated Pierre Salinger, the former presidential press secretary in the Kennedy White House, who had been appointed several months earlier to serve the remainder of the late Clair Engle's unexpired term. Murphy served from January 1, 1965, to January 3, 1971. Murphy assumed his seat two days early, when Salinger resigned from the seat to allow Murphy to gain an edge in seniority. Murphy was then appointed by Democratic Governor Pat Brown to serve the remaining two days of Salinger's term.