Back then, the enemedia (including "Uncle Walter") never told the American people about JFK's serious medical problems and the JFK/RFK sex scandals that made Slick Willie look like a rank amateur.
After LBJ, the candidates of both parties (but especially the Demonicrats) selected their VP choices at least partially on the VP's ability to be "assassination insurance."
The first Iever heard about JFK’s sex scandals, I was going to college and an elective I chose was “Law 101”. The lawyer/teacher took us on a field trip to the Federal Building in downtown Chicago. We visited the FBI and the Secret Service. If I remember right, the SS agent who was in charge of the Chicago office told us about JFK’s womanizing. He claimed that he was the agent that actually drove Kennedy to clandestine meetings with different women.