Link. It would cost his campaign nothing to test Super Tuesday. Stay and see, without buying any new ads. So why that smug and ambitious of an individual did not test it is the story you need to take away from him and who he's aiming to be -- becoming wealthy as a career politician. and later hopping the lobbyist gravy train or going to some Think Tank (a/k/a a retirement post). Harvard ticket punched. Rhodes Scholar ticket punched. Service ticket, McKinsey ticket, statewide name recognition run, DNC chair name recognition ticket, now the "good take one for the party stooge" ticket, so what more is needed? There is a career there, and the studied side-step is offered as proof of team player wannabe. Can't stand the guy. In my mind in a class with Biden and Bloomberg. Toxic.
Amy K at least has less to dislike, even if more the conservative on policy; with the "hard on staff" thing being uncertain while troubling. Amy is trustworthy. She has no child taking questionable directorships in foreign lands for big money. Warren would be the best brokered convention settlement option; Klobuchar second if it has to be that party wing keeping the crown jewels.
Beyond those two, Bernie or bust. Compromise beyond that, hell, give Orange Man four more if we are that disrespected by the inner party grubbers. Biden is a sad, sad, very sad joke, and a walking, talking four more certainty.
LAST - It is not Biden's "turn" anymore than last cycle was Hillary's. Inner party idiots insulated from reality would be the only ones thinking Biden would be tolerable, with a prayer of a chance to oust Orange Man. The people want Bernie. What he advocates. Being one of US. Being loyal to US. Over time.