Rule and Ruin: The Downfall of Moderation and the Destruction of the Republican Party, from Eisenhower to the Tea Party by Geoffrey Kabaservice Oxford University Press, 482 pp., $29.95

The abrupt departure of Rick Santorum from the Republican presidential contest on April 10, and reports on April 25 that Newt Gingrich had decided to withdraw, gave Mitt Romney a direct path to the nomination, though he was headed there anyway following narrow victories in Ohio (less than 1 percent) and Michigan (about 3 percent) and a wider one in Wisconsin (7 percent). Gingrich had been reduced some weeks ago to the status of heckling irritant rather than serious challenger. Santorum posed a stronger threat, but his wins, when they came, did little to alter Romney’s insurmountable lead in delegates, many of them won in caucuses. Even as Santorum swept to victory in Kansas in March, Romney quietly collected more delegates in Guam, the result of his superior funding and organization.

Nonetheless, a heavy toll has been exacted, not only on Romney but also on the GOP. After more than three years of fierce opposition to President Obama, Republicans have winnowed their choices down to a presumptive nominee who has failed to excite the party’s base, though not for want of trying. No less than his rivals, Romney diligently espouses current GOP orthodoxy, which holds that Obama incarnates a “radical” vision, like FDR and LBJ before him. After winning in Wisconsin—the primary that effectively ended Santorum’s run—Romney said Obama “has pledged to transform America, and he spent the last four years laying the groundwork for a government-centered society.”

Meanwhile, GOP chieftains, including House Speaker John Boehner and the arch-conservative Senator Jim DeMint, a Tea Party favorite, have said the time has come for the party to rally around the front-runner. Yet these endorsements have sounded more dutiful than enthusiastic. DeMint’s came on the same day, March 22, that Santorum, barnstorming in Texas, suggested that if the options in November came down to Romney vs. Obama, the incumbent would be preferable since “we might as well stay with what we have.”

This violated the GOP’s single unifying theme of “anyone but Obama.” But even after he was rebuked (by Gingrich, among others), Santorum returned to the theme. “Pick any other Republican in the country, but [Romney] is the worst Republican in the country to put up against Barack Obama,” he said while campaigning in Wisconsin. “We need someone who can go out and rally the Republican base,” which remains suspicious of “the moderate Establishment,” as Santorum has termed it—an establishment that today consists of such partisan redoubts as the Wall Street Journal editorial page, publications like National Review and The Weekly Standard, and Fox News, each of which, contrary to Santorum’s complaints, is firmly devoted to the dogma of movement conservatism.

Strategists at the top of the party’s pyramid may prefer a candidate they think will be palatable to independent voters in November. But true believers at the party’s base think differently. They don’t see a competition between two parties, with the prize to be…