I thought earlier today that this was unique. James Fallows, who knows more about the presidency than most living journalists, agrees:
To the best of my knowledge, nothing like this has ever happened before.
Presidents of one party call nominees from the other party “bad choices” or “wrong for America” or “risky bets” or in some other way second-best options to their own preferred candidate.
As far as I am aware, none of them has previously declared a major-party nominee categorically unfit.
Again we have two possibilities. Either Barack Obama, with a career’s worth of hyper-deliberate careful phrasing behind him, has suddenly made a lurch toward hyperbole. Or Donald Trump does in fact merit classification in an unfit category of his own.
Obviously I believe the latter is the truth. We’ll get to the pushback and ramifications in subsequent installments, including President Obama’s question to the Republican leaders who “rebuke” Trump but still support him: “What does it say about your party, that this is your standard bearer?”
For now, this is one more for-the-record note of how Campaign 2016 has crossed one more previously unexplored frontier.
It's really that bad.