The establishment GOP also has a batch of lesser tools at its disposal. Fueled by opposition research, it can malign troublesome candidates early, before they gain momentum, to cut off support and fundraising. A few Republicans with thick wallets could form their own super PACs, and, free from the controversy attached to a group like Crossroads, launch attacks. The party might be able to rely on the GOP’s business wing, fed up after October’s dual government-shutdown and default imbroglios.

The notion of an organic, grassroots push-back against the activist class by “mainstream Republican” rank-and-file is the establishment’s nirvana. Such an idea is generally mocked as implausible—moderate Republicans, by definition, are not as committed to the cause, and hence will always cede control to the more involved conservative hard-liners.

But in Iowa, the mecca of grassroots politics, the GOP is trying to prove the skeptics wrong. Most observers expect that the party’s nominee will be chosen at the GOP state convention, where some 2,000 delegates will gather. (Under Iowa rules, the nominee is picked at the convention if no candidate receives at least 35 percent of the vote, and few expect that anyone in a field that could ultimately run six candidates deep will cross the threshold.) Conventions often are a political disaster for Republicans—that’s how the losing Virginia ticket of Ken Cuccinelli and E.W. Jackson emerged—because only activists go through the four-step process to attend.

This year, however, establishment Republicans are recruiting mainstream voters to participate. “Getting people who don’t feel real strongly about anything to show up for a convention is a difficult thing to do, but because of things like the shutdown … they’re getting moderates roweled up,” said Doug Gross, a longtime GOP operative in Iowa. “Woody Allen was right: At least half of life, or 90 percent of it, is showing up.”