Error! Error! Error!
Robert F. Kennedy was elected to the United States Senate in November of 1964 and assumed his seat in January of 1965. Immediately prior to September 1964 he served as Attorney General of the United States under JFK and LBJ.
Clarification:
Robert Kennedy left office AS ATTORNEY GENERAL in September of 1964.
He and LBJ didn’t get along very well and LBJ wanted to pursue his own agenda.