The GOP has two fevers that need to break

The first is the tea party claim that ideological purity is the key to presidential success. Republicans, in this view, have lost recent presidential elections because their quisling candidates, John McCain and Mitt Romney, could not turn out 4 million “missing” conservative voters.

That number, it actually turns out, is a myth, rooted in the slow reporting of vote totals after the 2012 election. “There’s no magic formula,” said Dan McLaughlin of RedState, “no cavalry of millions of conservatives waiting just over the hill to save the day.” A Custer-like loss by Cruz — who has shown little ability to expand beyond his narrow ideological appeal — would demonstrate this point.

The second fever is less common in the United States than in Europe, but it is a particularly vicious strain. This is the claim by right-wing populists that Republicans need to completely reorient their ideology in favor of nativism, protectionism and isolationism in order to appeal to working-class whites. This was the message of Pat Buchanan’s presidential campaigns starting in the 1990s. With Trump, it is back in full force.

The problem? Aside from the fact that protectionism is self-destructive economic policy, and isolationism is disastrous foreign policy, an attempt to pump up the white vote with nativist rhetoric alienates just about everyone else.