Geoffrey Kabaservice has written for numerous national publications and has been an assistant professor of history at Yale University. He is the author of the National Book Award-nominated The Guardians: Kingman Brewster, His Circle, and the Rise of the Liberal Establishment and, most recently, Rule and Ruin: The Downfall of Moderation and the Destruction of the Republican Party, From Eisenhower to the Tea Party. He lives outside Washington, DC. Rule and Ruin was reviewed in this Sunday’s New York Times.

It’s hard not to feel at least a little sorry for Iowa’s conservative Republicans. Although three-quarters of the votes in Tuesday night’s caucus went to conservatives of one stripe or another, the winner by a bare eight votes was Mitt Romney, the most moderate candidate running – and “moderate” is an obscenity for conservatives. They don’t like Romney, and the feeling seems to be mutual. But even the relatively moderate Iowa Republicans who voted for Romney don’t seem terribly excited by him. The word his supporters most commonly use to describe him is “electable,” which is faint praise on the order of calling a meal “edible.” Nonetheless, his Iowa victory makes it all but certain that the former Massachusetts moderate, despite being the least preferred candidate of a majority of Republicans, will be the party’s champion for the presidency in 2012. This is an unhappy marriage of convenience that even Madame Bovary might pity.

Why are the Republican front-runner and the party’s base so at odds with each other? The answer lies in the party’s history, and particularly in the tension between moderates and conservatives that has been a constant theme of the GOP since the first incarnation of the New Right coalesced around the red-baiting Senator Joseph McCarthy in the early 1950s.

The conservative movement has flared up at regular intervals ever since, like cicadas or herpes. Barry Goldwater’s presidential candidacy in the early 1960s was followed by Ronald Reagan’s efforts in 1976 and 1980, the Newt Gingrich-led Congressional insurgency of 1994, and the Tea Party over the past several years. In all of these incarnations, the primal enemy for the conservative activist has been not so much the liberal Democrat as the moderate Republican.

In the conservative view, the Democrats are foes to be overcome, but moderates are traitors to be exterminated. Moderates strike conservatives as a haughty establishment, unresponsive to the people’s wishes and in thrall to the elite media and “informed opinion.” Were it not for the moderates’ unprincipled willingness to compromise with Democrats, so the conservative thinking goes, the welfare state would long since have been repealed, and few of the pernicious progressive developments of the twentieth century would have come to pass....