Thus far, President Obama has primarily been worried about his left flank as he sends more troops to Afghanistan. He should be just as worried about his friends on the right. I fully expect that over the next year Republicans will begin to abandon the president en masse over Afghanistan.

Obama’s saving grace on Afghanistan has been that conservatives, from the Republican leadership in Congress to Sarah Palin to leading foreign-policy thinkers like Bill Kristol of The Weekly Standard, have backed a troop surge and have been mostly willing to back the White House on this particular issue. But now Rep. Jason Chaffetz, a Utah Republican known for his independent streak, has made a conservative case for withdrawal. And my guess is that by the 2010 congressional elections, dozens of Republican candidates will be doing the same across the country.

There is a growing sense that the U.S. military is too hamstrung by concern about civilian casualties and political correctness to wage an effective military campaign under Obama.

• Tina Brown: Obama’s Fog of War • Lee Siegel: The Zero-Sacrifice Presidency Last month, a CBS News poll found that just 23 percent of Democrats believe that an increase in the number of U.S. troops will improve the situation, and some of the party’s 2010 candidates are already on record as opponents of the surge, including Arlen Specter and would-be Ted Kennedy successor Martha Coakley. Throughout the long presidential campaign, Barack Obama called for winding down the American presence in Iraq to focus on the rapidly deteriorating security situation in Afghanistan, so there is no sense the president is pulling a foreign policy bait-and-switch. But among Democrats, and particularly left-of-center Democrats, there is a pervasive sense that the Obama administration has proved too cautious and centrist on domestic issues. That means there is less willingness to give the president the benefit of the doubt on waging an expensive counterinsurgency, particularly as many of the left’s domestic priorities could well be sacrificed on the altar of deficit reduction.

And so the president is caught in an extremely awkward position. Abandoned by the Democrats, he is relying on the support of a shrinking centrist foreign-policy establishment that, to put it bluntly, has zero political muscle. The conservatives who back the troop surge don’t think the president is going far enough, and most expect that his effort to craft a compromise counterinsurgency will fail. Among grassroots conservatives, there is a growing sense that the U.S. military is too hamstrung by concern about civilian casualties and political correctness to wage an effective military campaign under Obama, which implies that there is little point in offering him political support.

In a statement on his House Web site, Chaffetz makes the point explicitly. Deriding the idea of a counterinsurgency strategy, he writes, “our military is not a defensive force for rough neighborhoods around the world.” Rather than fight to protect Afghan civilians, Chaffetz argues that U.S. forces should focus exclusively on al Qaeda’s threat to the homeland by targeting and killing its members. In essence, Chaffetz is recognizing the contradiction at the heart of what had been bipartisan support for the U.S. mission in Afghanistan: Americans have supported the war effort insofar as it is designed to keep Afghanistan from becoming a safe haven for al Qaeda. But the consensus among foreign-policy experts is that the safe-haven argument is weak: The tribal areas of Pakistan and Yemen and Somalia are far likelier candidates for a safe haven, and Islamist terrorists also are found in American and European cities. The more sophisticated case, made by conservative foreign-policy intellectuals like Christian Brose and Daniel Twining, rests on the need to shape Pakistan’s behavior. As strong as this case may be—I happen to think that it is completely correct—it isn’t very politically potent, particularly when it looks to the American public as though U.S. soldiers are dying to protect one group of Pasthun tribesman from another.

Chaffetz’s argument resonates strongly with what Walter Russell Mead has referred to as America’s Jacksonian tradition. In a 2003 interview, Mead described the Jacksonians as being a bit like bees: “When somebody attacks the hive, you come swarming out of the hive and you sting them to death.” The goal isn’t to go abroad to build friendships across cultural divides or to heal the sick. Rather it is to ferociously punish anyone who dares attack the United States. Jacksonians thus have little regard for civilian casualties—they don’t believe in limited wars. By its very nature, a counterinsurgency campaign is a limited war, one that relies on winning over the civilian population through the careful use of military force combined with deft diplomacy. The idea is to use persuasion as much as possible and coercion as little as possible. So when Chaffetz writes that we’ve tied the hands of our military, he means that vanquishing enemies, not nation-building, should be our core goal.

Remember that the bitterest opponents of the Clinton-era U.S. interventions in Kosovo and Haiti were conservatives like Tom DeLay, who condemned the Clinton administration for treating “foreign policy as social work,” in Michael Mandelbaum’s evocative phrase. The post-9/11 moment represented a departure from this conservative suspicion of nation-building, as Jacksonian sentiments were yoked to the ambitious project of building democracies in the Muslim world. But now that Obama, a man most conservatives dislike and distrust, is the steward of that effort, those conservative instincts are making a comeback. Jason Chaffetz represents the beginning of a wave—and it’s not obvious that Obama can do anything to stop it.

Reihan Salam is a fellow at the New America Foundation and the co-author of Grand New Party.