New York Mayor Bill de Blasio's campaign is a mystery. He seems to have no popular support, at home or in Iowa. He's been an afterthought in the race so far, so it's fitting that he had to angrily elbow his way into tonight's debate by attacking former Rep. Beto O'Rourke while the latter was speaking.

De Blasio slammed O'Rourke for saying he wanted to let people keep their private health insurance if they so chose. In fact, de Blasio and Sen. Elizabeth Warren were the only two candidates on stage who committed to abolishing private insurance.

But de Blasio's hectoring was unmemorable. What was much more memorable was that the mayor of the world's capital was then abruptly put in his place by some bald dude who seemed to have wandered onto the stage from nowhere.

His name is former Rep. John Delaney, D-Md.. You wouldn't know this, but he was actually the first Democrat to announce for president. No one knows who he is, but he offered the factual rebuttal to Medicare for All in front of a Democratic debate audience and lived to tell about it. That makes him a hero in my book. More people need to hear that if healthcare is paid for at Medicare reimbursement rates, then hospitals and providers will simply close. This is why President Obama wasn't daft enough to try such a thing.

Watch Delaney's explanation here: