Wisconsin proves Trump can dish it out, but he can't take it.

Five years ago, it seemed it would go on and on when Barack Obama in his role as master of ceremonies at the Washington Correspondents Dinner jumped on Donald Trump because the shrill billionaire was spreading the tea party movement's conspiracy theory that the president was foreign-born. Trump's smirk got smaller and smaller over the ensuing years until it finally disappeared silently into the night.

After the Iowa kickoff, the Wisconsin primary election showed beyond doubt what a poor loser the tycoon with the super-ego truly was. His opponent Ted Cruz characterized him as a Trojan horse and a puppet, and the Republican elite began closing ranks against him but he has — first and foremost — only himself to blame for ignoring women's issues and lacking consistent ideas that go beyond clumsy slogans.

That he sent his wife Melania, the ex-model, in for the final stretch turned out to be counterproductive. “When you attack him, he will punch back 10 times harder,” she told the crowd. But he often aims below the belt. And sticking to boxing terminology, the guy's got a glass chin. He's great at dishing it out, but he can't take it. That's not a good quality in any politician and definitely not in a president.