But immigration isn’t just another issue, like farm subsidies or taxes or even battling radical Islam. Immigration is a meta issue, one that affects almost every arena of national life — from politics to education to jobs to security to health care to national cohesion. If we set taxes too high, we can lower them later. If we let the Navy get too small, we build more ships. But if we get immigration wrong, we can’t undo it: People are not widgets, and we can’t ask for a do-over after adding 30 million green cards in a decade.

What’s more, the deep gulf in views over immigration between elites and the public, between globalists and patriots, has given immigration a symbolic importance as a marker of legitimacy. As Ramesh Ponnuru has written, “A hard line on immigration, however it is defined, is now part of the conservative creed.”

In effect, Rubio is an Angela Merkel Republican — genuinely conservative on most every issue, except the one that counts above all others.

For this reason alone, he should be denied the nomination. If he were to succeed in getting it, the donor class and its politicians would take away the lesson that they can betray the voters all they want on this potentially nation-breaking issue, and simply talk their way out of it. Voltaire wrote, in Candide, that “it is good to kill an admiral from time to time, in order to encourage the others.” Rubio’s betrayal doesn’t warrant the gallows, but he must be denied this prize, “in order to encourage the others.”