It’s no longer business; it’s personal. Cruz has essentially declared that he couldn’t support someone who did what Trump did to Heidi Cruz. He might try to patch relations with some Trump supporters — is Chris Christie’s soul still for sale? — but how many could he peel away? Remember: Wisconsin has just demonstrated Trump’s unbreakable core.

And if Trump loses out, a split is guaranteed. In Trump’s mind, he is a winner. Always. If he loses, it can only be because he was cheated. He constantly contends that he’s being treated unfairly. He is certain to declare any convention process that leaves him without the nomination irredeemably unfair. No need to go third party. A simple walkout with perhaps a thousand followers behind will doom the party in November. In a country where only 25 percent feel we’re on the right track and where the leading Democrat cannot shake the challenge of a once-obscure dairy-state socialist, you’d think the Republicans cannot lose.

You’d be underestimating how hard they are trying.