Kennedy lives: Who do the Democrats nominate in 1968?

Exactly what it says on the tin. John Kennedy is never assassinated. Without getting into a lot of arguments over what happens in 1964, presume Kennedy is a two term President. After Kennedy's years in the White House, the Democratic Party is tasked with selecting a successor. Now in my view, the two most discussed successors for President Kennedy in 1968 are not particularly plausible. I doubt LBJ would run. Johnson's decision not to seek the Presidency in 1968 was not merely the consequence of New Hampshire. He was afraid of his health failing during a 1969-1973 term, and he was generally terrified of dying in office. While the Presidency's extra stress doubtlessly took its toll, Johnson may have similar health concerns come 1968 ITTL. And I very much doubt Robert Kennedy is going to get the nomination when his brother's Presidency ends. So, if not Vice President Johnson or the President's brother, who might the standard bearer be? Hubert Humphrey?
 
I wonder if it's someone we wouldn't jump to IOTL. Would JFK and co seek to groom a successor in the last two years of his Presidency? Norton and RB are the go-tos in this situation.
 
Most likely Hubert Humphrey, who picks either Terry Sanford or Carl Sanders as his running mate. GOP still nominates Nixon.
 
Same as OTL. I'd bet on a Humphrey victory, even if JFK is less popular than Johnson in '68, since Humphrey won't be as tied to the Administration.
 
Most likely Hubert Humphrey, who picks either Terry Sanford or Carl Sanders as his running mate. GOP still nominates Nixon.

Why not Johnson? He'd be chomping at the bit to be the nominee and he'd have support of the Party Bonzen
 
JFK did not want LBJ to succeed him. Not out of animosity (none existed, their relationship was rather decent) though. LBJ's health would probably rule it out as well, like Glass Onion mentioned.
 
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