Of the 11 men who've served as US President since WWII, the breakdown regarding the highest level jobs they held prior to their elections is:

Army General: 1 (Eisenhower)
Senator: 1 (Kennedy)
Governor: 4 (Carter, Reagan, Clinton, Bush II)
Vice President: 5 (Truman, Johnson, Nixon, Ford, Bush I)

Of those who were vice presidents, Truman, Johnson, and Nixon were senators before that, Ford & Bush I had been congressmen (tho Bush I had also been ambassador to the U.N. and head of the CIA in betweentimes).

~ Becky in Tucson