The government shutdown may turn out to have been the high-water mark — the Cemetery Ridge — of the tea party movement. In the aftermath, House Speaker John Boehner declared that tea party groups had “lost all credibility” and Senate Minority Leader Mitch McConnell promised that the party would “crush” outsiders targeting incumbents. The next two months of primary battles will determine the final tally of the squashed. But high-profile tea party challenges in many places — including Kentucky and South Carolina — have faded.

The GOP establishment backlash has been successful for a particular reason: It has been led by politically rational conservatives, not the RINO moderates of tea party nightmares. Rockefeller Republicans are as rare as giant pandas; both cause passersby to point and gawk. The consensus among Republican legislative leaders and prospective presidential candidates is Reaganite (or right of Reagan) in most respects. So the tea party revolt must not only fight against RINO enemies, it must imagine them.

For some tea party groups and leaders, an ever-narrowing orthodoxy is the objective. Their approach resembles the more extreme forms of Protestantism, in which a passion for doctrinal purity divides and divides until there is a true church of one. The Republican Party, constituted to win majorities, has begun pushing back in primary contests. Which is necessary, and not sufficient.