Mr. Cruz, who used to be fond of calling Mr. Trump “my friend Donald” when it seemed opportune, now presents himself as the only man standing between his nemesis and the nomination. But Mr. Cruz’s trashing of his fellow Republicans hastened the arrival of the ultimate party-crasher. Arsonists who set fire to their neighborhood run the risk of burning their own house down.

And then there is the GOP rank-and-file. It is supposed to be sinful for conservative columnists to blame Republican voters for making disastrous choices, at least without the obligatory nods to their patriotism and pain.

But if Democrats don’t get a moral pass for bringing Bernie Sanders this far in the race, Republicans shouldn’t get one for bringing Mr. Trump to the cusp of the nomination. The point of democracy isn’t freedom. It’s political accountability. That goes for elected officials—and for the ones who elect them.

The “white working classes” that are said to form the core of Mr. Trump’s support deserve better than to be patronized with references to their “anger.” They deserve to hear an argument about the disaster they are about to impose on their party, their country and their own economic interests.