"In short, Gephardt pointed out, a third-party bid could never succeed on its own; it would mostly take votes away from Biden. Manchin absorbed the argument, the person says, and then expressed an acute worry: Above all, Manchin said emphatically, he did not want to become the person who handed the presidency to Trump.
That argument finally seemed to prevail with Manchin last week, when he announced that he will not be part of any third-party ticket after all."
Well, thank you, Richard Gephardt. Both for talking sense to Manchin and being a person Manchin trusted.
https://newrepublic.com/article/179244/no-labels-spoiler-bid-manchin-meltdown-mode