The de facto endorsement of François Hollande is the kiss of death for Emmanuel Macron.
I told you. Jean-Luc Mélenchon is the man.
The other candidate would be bound to win. That has happened in the past.
Why, then, should that candidate not be Mélenchon?
Whoever is the second round candidate against Marine Le Pen will be guaranteed to beat her.
Therefore, it is possible, and thus morally obligatory, to insist on the right candidate.