“Someone has to bring him down,” he told reporters in the lounge of the St. Louis Marriott. “I’m not going to sit quietly by and let the disaster that is Donald Trump become the nominee. Do you want someone who appears to still be in grade school to be in charge of the nuclear arsenal?”

Paul later told me he thinks he has found an approach that will separate Trump from the rest of the GOP field: eminent domain.  “A hallmark of Republicans is that they respect private property. But Trump runs roughshod over it,” he said. “He is a serious abuser of taking property for his private benefit.”