Platner

This appears to be catastrophic.

Whether he stays in or drops out it's a clusterf%$#.

If he stays in, he's a crippled candidate, and if he is replaced by one of the usual suspects by the Democratic Party establishment (There is no Democratic Party establishment) it will demoralize a significant portion of potential Democratic voters.

One of the biggest challenges in the November elections is that voters will choose the couch (aka JD Vance's girlfriend) over the voting booth, and I do not see how this won't make this more likely regardless of final outcome. 

If he drops out, and he is replaced with Janet Mills or someone of her ilk, that would just make a bad situation much worse, but this won't stop the Democratic Party establishment (There is no Democratic Party establishment) from doing just that.

It's the Iron Law of Institutions, "The people who control institutions care first and foremost about their power within the institution rather than the power of the institution itself. Thus, they would rather the institution "fail" while they remain in power within the institution than for the institution to "succeed" if that requires them to lose power within the institution." (Not my idea or term, this term was coined by Jon Schwarz)