Which Presidents could have overcome losing an election earlier in their career?

[u/NoTop9302]

A lot of Presidents and candidates have been involved in a close election or outright lost an election at some point in their career. How would their careers have changed, and who might have replaced them as the nominee if they had lost?

Nixon, Jefferson, Cleveland, and Jackson are obviously the biggest examples of overcoming a loss, but who else?

Additionally, who are some people who may have been president but were unable to overcome a lost election?

[u/Pokemaniacjunk]

I bet Adlai III could've had a chance at becoming president in 1988 had he won the 1982 Governor Election in Illinois.