In my view, Al Gore knows in his heart that he cannot win the nomination, and therefore does not want to set himself up for a loss of this magnitude.
He wants to leave his political legacy intact, not in shreds.
There is no way he wouldn't win the nomination and there is a fairly good chance he would win the general. However, you are somewhat right in that he is afraid of "losing" again. To lose something twice on such a huge scale in front of the entire country is very difficult. Especially if your first loss was really a win you weren't allowed to claim.
If Gore were to run, I would guarantee you that he would become the next POTUS. I don't see any way he could lose, and I hate Gore.
