W

RFK : Д :: _______ : Ψ, where Д is the year of the historic presidential candidacy of a Senator who was later defeated by a Senator who was later defeated by a Senator who later served as the Secretary of Defense who immediately preceded the return of the only Secretary of Defense to serve two different Presidents, and Ψ is the year in which a former New Hampshire primary winner who did not win his party’s nomination that year, who shares the surname of a former President from a different party, ran a third party candidacy for the Presidency. (14 letters, 2 words)