I know that a lot has been written about the possibility of Kennedy dumping Johnson from the ticket in 1964 and choosing a new Vice Presidential running mate, but I never bought into those suggestions.
First of all, JFK needed LBJ to win Texas in 1960 and would have needed him to win Texas in 1964. Texas was an immensely important state on Kennedy’s electoral map and probably no other Vice Presidential choice could have helped JFK win Texas other than LBJ. LBJ was also immensely important to any political strategy for the South. One of the names suggested for replacing LBJ if JFK had lived and dumped Johnson was Florida Senator George Smathers (a close friend of JFK), and Smathers would have helped in the South, but not in Texas.
The main reason that I feel like Kennedy wouldn’t have dumped Johnson from the ticket in 1964 is very clear: November 22, 1963. Now, we all know that that’s the day JFK was assassinated, but we sometimes overlook the fact that JFK was in Dallas because he was making a swing through Texas that was basically an unofficial kickoff for the 1964 reelection campaign. Why does that matter? Because LBJ was prominently featured in events throughout the Texas trip and I think JFK was even scheduled to stay at the LBJ Ranch the night he was killed. If the plan was to drop Johnson from the ticket, he would not have been such a visible presence during the Texas trip.
Still, the rumors persist today, and they were widespread even back in 1963. On the day of JFK’s assassination the headline in the Dallas Morning News read “Nixon Predicts JFK May Drop Johnson”. A few weeks before the assassination, a reporter asked President Kennedy directly if he wanted LBJ on the ticket in 1964 and if he expected LBJ to be on the ticket. JFK responded, “Yes to both those questions. That’s correct.” JFK’s closest aides echoed those statements. Arthur Schlesinger said that the idea of dropping Johnson from the ticket in 1964 was “wholly fanciful”. In a private remark about the possibility, JFK said it was “preposterous”. After JFK’s death, Bobby Kennedy — no fan of LBJ — said that there had been no intention of dumping LBJ for another Vice Presidential candidate.