It’s not pretty, but it’s really something to behold—an extended, angry, sneering, vindictive attack on Carson’s character and biography that would be unimaginable coming from any other candidate. Trump’s argument, to the extent that it can be summarized, is that the press has been trying to paint Carson as an exaggerator, when the real problem is that Carson claims to be telling the truth about his history of violent incidents. As usual, Trump, in his ugly, unhinged way, has managed to zero in on his rival’s biggest potential weakness.

Yet at the same time, he may have revealed his own. Trump’s attack on Carson comes across not only as typically (for Trump) aggressive, but as unusually anxious. More than any other candidate, Carson seems to have rattled Trump.

Trump claims to be mystified about Carson’s success in the polls. “That’s who’s in second place,” he says of Carson, after describing the neurosurgeon’s history of outbursts. “And I don’t get it.”