What forces thrust HHH forward?
It appears me to have been a Deep State operation. Humphrey was compromised by being part of the Johnson war efforts but they thought he had enough cover to survive it. As it was the War continued for another 3 or 4 yrs.
I don’t buy LBJ’a explanation - that he was doing it for the good of the country. LBJ was one of the biggest egomaniacs ever to hold that office and one of the most murderous.
Hump was a much weaker leader and would not be able to withstand pressures that LBJ did for four years..