One of the virtues of American democracy is that sleazy tricks like that don’t work. In France, where there are two votes, two weeks apart, the second pitting the two strongest candidates when no one gained a majority on the first ballot, tactical withdrawals are not rare. Any attempt to carve up the Republican vote in a deal between Messrs. Cruz and Kasich where each would run a straw campaign only where the other was stronger in the remaining primary states would be so mortifyingly denounced, by Mr. Trump, as the imbecilic scam that it would be, it would accelerate his nomination.

As for Mr. Kasich’s retiring from the race, there is no reason why he should do so, unless his candidacy has no legs at all in the next few weeks. That could happen, though he has more natural support than Mr. Cruz, and if he does withdraw, he is unlikely to recommend to his supporters how to vote. Mr. Trump should get as many of them as Mr. Cruz does, as Messrs. Trump and Kasich are closer in policy terms, and even in being less hard-edged and more jocular personalities than Mr. Cruz.

The idea that Mr. Cruz, with all his abrasions and nasty techniques (prematurely announcing the departure of Ben Carson from the race, blaming Mr. Trump for the leftist demonstrations against him, accusing Mr. Trump of ambivalence toward Israel, etc.), could suddenly morph into a unity candidate for all Mr. Trump’s foes on the frightened left and under-indulged right is bunk.