This happens to everyone who tops the polls.See the smear campaign against Bernie is in full flow now. Conveniently a couple of days after Trumps campaign aknowleged he was a threat.
He's now apparently mysogenistic, stating a woman cant be president, even after multiple videos have surfaced of him actually saying the opposite.
Sanders sent his volunteers out with scripts to trash Warren despite agreeing not to.
Buttigeig has been trashed for not disclosing his Mckinsey work or his donors or his relationship with African Americans.
Warren has been trashed for not being working class/likeable enough.
But Biden has been trashed by far the most, for pretty much everything.
As soon as there is the slightest Democratic criticism of Sanders, the paranoia kicks in.