The GOP's conservative wing, after all, has many chambers. There are social conservatives, whose support for "pro-family" government regulation rankles some economic conservatives. The latter group, in turn, is divided between tax-cutting supply-siders and budget hawks who worry that deficits impinge on growth. Then there are foreign policy and national security conservatives -- some of them isolationists, others interventionists in the name of advancing America's global interests. And don't forget libertarian conservatives such as Rep. Ron Paul (R-Texas), who don't share much with social and national security conservatives beyond their love of low taxes.
Reflecting those divisions, multiple conservative interest groups have rated McCain's voting record, and their score cards have yielded widely divergent results. In 2006, for instance, his ratings included high marks from the deregulation-loving Americans for Prosperity and the earmark-hating Citizens Against Government Waste, but failing grades from Phyllis Schlafly's family-values-oriented Eagle Forum and the John Birch Society, which these days focuses on closing the borders.
More than his votes on specific bills, though, conservatives have been rankled by McCain's unpredictability and his willingness to (gasp!) work with Democrats on shared priorities such as immigration, election law and greenhouse gases.
Bush, on the other hand, has been nothing if not predictable, and he has rarely formed common cause with Democrats. Yet many conservatives have soured on him too for presiding over an orgy of deficit spending, miring the U.S. in a futile nation-building exercise in Iraq, ruining the American brand overseas and -- worst of all -- damaging the GOP's reputation so badly that Democrats regained control of Congress.
Perhaps McCain's best fence-mending hope is to win the backing of a conservative icon whose appeal spans the factions -- someone like, say, a certain bombastic radio host. Don't look for Rush Limbaugh to switch from criticizing McCain to lavishing praise on him, however. He said Wednesday: "If I endorse McCain, all these independents and Democrats that despise me would abandon him. I'm the greatest asset McCain has." That clapping sound you hear is Karl Rove, the master of rallying the GOP base to win elections, slapping himself on the forehead.