bostonknight

No one has been elected to the Presidency of the United States after having served only in the Senate since JFK. And even he seems to be an anomaly:

Taft No previous elected office, Presidential appointee
Wilson Governor
Harding SENATOR, Lt. Governor, State Rep Ohio
Coolidge VP, Governor, Lt. Governor, Assumed first term as President
Hoover No previous elected office, Presidential appointee (generally regarded as a failure in office)
FDR Governor
Truman VP, Assumed first term as President, Senator
IKE General
JFK SENATOR
Johnson VP, Assumed first term as President, Senator
Nixon VP, Senator
Ford Never Elected, Assumed Presidency, US Representative
Carter Governor
Regan Governor
George I VP, Presidential appointee, US Representative,
Clinton Governor
George II Governor