In this alliance, most observers of the Republican Party would agree, the business-friendly conservatives (Pew’s Enterprisers) are clearly the senior partners, religious conservatives are the junior partners and the pro-government populists get deficit-funded spending in boom times and table scraps when things get tight.

But the Enterprisers’ hold on policy making is vulnerable, should religious conservatives and populists both rise against them — which is what many primary-season insurgencies have tried to do. From Pat Buchanan in 1992 and 1996 to Mike Huckabee in 2008 to Rick Santorum four years ago, various would-be outsiders have effectively sought to rally a united front of religious conservatives and populists, in hopes of renegotiating the terms of the coalition’s partnership.

They all failed. In 2016, though, something new is happening. A united front isn’t being forged; instead, we have both a religious conservative and a populist insurgency, the former led by Ted Cruz and the latter by that most unlikely populist, Mr. Trump.