John Mearsheimer, one of the pre-eminent representatives of the realist school of international relations, voted for George W. Bush in 2000. But not this time. Come November, he's not only voting for John Kerry but "will do so with enthusiasm."

As a realist, the University of Chicago political scientist liked Bush's anti-nation-building rhetoric during the 2000 debates, and was displeased by Al Gore's support for the humanitarian interventions of the 1990s. But Bush's handling of foreign policy -- particularly the Iraq War -- has turned Mearsheimer and other realists into some of the administration's sharpest critics. "[T]he more time goes by," he says, "the more Bush makes [Bill] Clinton look like a genius in both domestic and foreign policy."

Indeed, not only is the American right a house divided on Iraq but over the intensifying imperialist drift of U.S. foreign policy more broadly. A convergence of realists, libertarians, and traditionalists (or "paleocons") has taken shape in opposition to the neoconservative foreign-policy agenda. In October, they came together to form the Coalition for a Realistic Foreign Policy, which holds that "the move toward empire must be halted immediately."

Spearheaded by Christopher Preble, director of foreign-policy studies at the Cato Institute, the coalition's signatories include Mearsheimer and fellow realist Stephen Walt of Harvard; Andrew Bacevich, author of American Empire: The Realities and Consequences of U.S. Diplomacy; Ted Galen Carpenter and Charles Peña of Cato; Christopher Layne and Scott McConnell of Pat Buchanan's magazine, The American Conservative; and Jon Utley of the organization Americans Against World Empire. A handful of left-of-center types are also onboard, among them Blowback and Sorrows of Empire author Chalmers Johnson, Anatol Lieven of the Carnegie Endowment for International Peace, and former Colorado Senator Gary Hart.

"Empire is problematic," reads the group's founding statement (titled "The Perils of Empire"), "because it subverts the freedoms and liberties of citizens at home while simultaneously thwarting the will of people abroad." "The defenders of empire," it goes on, "assert that the horrific acts of terrorism on September 11, 2001, demand that we assume new financial burdens to fund an expansive national security strategy, relax our commitment to individual liberty at home, and discard our respect for state sovereignty abroad. Nothing could be further from the truth." The group calls for the United States to jettison its imperial designs and adopt in their place a "restrained and focused foreign policy" for the 21st century.

Members have gone public with their concerns. Writing in the October 6, 2003, issue of The American Conservative, Layne argued that the Bush administration's "go-it-alone hubris" and "sledgehammer diplomacy" have led to a "fiasco" in Iraq -- "[a]nd a foreseeable one at that." McConnell, that magazine's executive editor, wrote that with their "incessant warmongering," the "belligerent" neocons have "led the United States into an extremely perilous situation, perhaps the most dangerous in its history." And Walt, in a talk before the Council on Foreign Relations, said that the case for the invasion of Iraq is "empty," a "combination of bad history, inconsistent logic, wishful thinking, and old news." The realists' case against the war gained perhaps its widest visibility with the publication of Mearsheimer and Walt's "An Unnecessary War" in the January-February 2003 issue of Foreign Policy, an article that radiated across the Internet and stirred far-reaching discussion.

Though this alliance against the expanding imperium is a work in progress, the phenomenon's raw ideological ingredients are nothing new. Self-styled traditionalists or paleocons like Buchanan have been arguing since the end of the Cold War that America should be "a republic, not an empire." Libertarians, deeply suspicious of "activist" government, were consistently against all of the interventions of the 1990s -- Somalia, Haiti, Bosnia, Kosovo, East Timor -- and are positively choleric in their opposition to the global designs of Team Wolfowitz. And the realists have long maintained that the United States should go to war only when its vital national-security interests are at stake, with most realists believing that Iraq did not meet that standard. Realists figure prominently in the foreign-policy establishment, staffing institutions like the Council on Foreign Relations. The council, itself divided over the war, held a debate in February 2003, with the anti-war Mearsheimer and Walt squaring off against the neocon Weekly Standard's William Kristol and Max Boot, who advocated invasion.

The first Bush administration, says Mearsheimer, was a "paradigmatic realist administration." The current Bush administration "looked a lot like Bush I" in its first few months. The events of September 11, however, "flipped" Dick Cheney from the realist camp to the neocon credo. Up until 9-11, the neocons "could get to first base with their agenda but no further," Mearsheimer says. After the terrorist attacks, "they were able to make it all the way."

Of course, the handful of conservative intellectuals who vote against Bush won't change the upcoming election. The threat to the president's support, says conservative commentator David Brooks, is in the "George Will wing" of the Republican Party -- people, that is, who say, "'We're conservatives -- we don't think you can remake societies.' ... And I do think there are a lot of conservatives who share that sense." The conservatives Brooks is talking about didn't oppose the war; it's more the aftermath that worries them. (Though Will was a vociferous advocate of the administration's drive to war, he did something of a volte-face in a speech at the conservative Manhattan Institute in November 2003, when he expressed grave doubts about the larger democracy-spreading ambitions of the war's neocon architects. He also regularly pelts frequent guest Richard Perle with incredulous demurrals Sunday mornings on ABC's This Week.) People in this camp "don't have a sense that the White House knows what they're doing" in Iraq, he says, adding that he detects a hard-to-quantify "coolness" toward Bush among conservatives around the country.

Divisions among conservatives have mattered politically in the not-too-distant past. Indeed, says Kenneth Hoover, a professor of political science at Western Washington University and a student of ideological tensions on the right, they "brought down [Margaret] Thatcher and [George] Bush Senior." "Bush's advisers are nervous about these splits," he says, pointing to the administration's "go-for-broke strategy to get through as much of their agenda on taxes and deregulation in the first term as possible." He adds: "The cracks are beginning to show among conservative elites and the masses are getting restless, judging from the polls. ... One wonders how much faith the insiders really have in the re-electability of their leader."

But it's a funny thing: despite these symphonies of anti-war opinion on the right, these same voices have been largely absent from the conservative press. The op-ed page of The Wall Street Journal has carried only a single anti-war piece by a conservative. FOX News has had only one anti-war conservative on the air to opine about Iraq. (Pat Buchanan has appeared on Hannity & Colmes twice and On the Record once. The O'Reilly Factor has had two people from the Cato Institute who opposed the war, Preble and Peña, but neither was on specifically to discuss his opposition to the war.)

I asked Paul Gigot, the Journal's editorial-page editor, for an explanation. "We ran the most influential anti-war op-ed by any conservative," he replied, referring to the widely discussed August 15, 2002, piece by Brent Scowcroft, a quintessential realist who served as national-security adviser in the Ford and Bush Senior administrations. "We're not an all-things-to-all-people op-ed page," he says. "We're not trying to censor any argument. We just have to deal with the major arguments" -- and the libertarians and the paleocons "are not major points of view. I don't look to the Cato Institute or any of their writers for instruction on foreign policy. Is libertarianism a school of thought, or is it four or five people in a phone booth?" As for the paleocons, says Gigot, "[E]ssentially they make the same argument as most of the people on the left do. When I read one of their pieces, it sounds to me like it could come right out of some parts -- not all parts, but some parts -- of The Nation."

This should come as no surprise, say several conservative critics of the war. "The Wall Street Journal is like Pravda," says Mearsheimer. "You don't want to underestimate the importance of the Leninist model," he says, with regard to the American right. "They don't tolerate dissent."

Christopher Preble wants the Coalition for a Realistic Foreign Policy to challenge the conservative party line, and particularly the "empire fever," currently infecting the country. "The time for debate," the coalition states on its Web site, "is now" -- a rallying cry the group's members are attempting to discharge by hosting forums and conferences, publishing papers and articles, and appearing on television and radio to articulate the case against empire. On April 19, the group hosted an "American Imperium" conference on the campus of Swarthmore College.

Still, it's by no means clear that all the group's members are planning to vote for Kerry. Preble says he sees "no substantial difference" between Bush and Kerry on the issue of the war, and finds Kerry's position on the occupation "less defensible" than Bush's. Still, the coalition's front man says he has "never been this conflicted" this late in the game, and that he hasn't yet made up his mind between Bush and the Libertarian Party candidate.

In contrast, Harvard's Walt, another member of the coalition, does plan to cast his ballot for Kerry. "He understands much better than the Bush administration does that, in fact, the United States, despite its preponderance of power, can operate most effectively when it operates with substantial international legitimacy and support," explains Walt, who says he has voted for both Democrats and Republicans in the past. Team Bush, he says, has "presided over a deterioration of the situation in the Middle East, a dramatic deterioration of America's overall image overseas, in every part of the world." He adds, "I don't think there's been an administration that had as much contempt for the truth, in policy terms, as this one. ... [W]hy would you believe anything a senior administration official told you?"

The war was the single issue on which Pat Buchanan says he could have agreed with a Democrat, but given Kerry's support for it, Buchanan says he "simply could not" vote for the senator. At the same time, he adds that there is "no conservative party in Washington today." Buchanan disagrees with Bush not only over Iraq but on trade, immigration, and the deficit -- issues on which he says the president is "very vulnerable from the right. ... I think you could run a populist-conservative campaign and siphon off enough votes" to defeat Bush, he says. Plenty of people have asked Buchanan why he's not taking up the task himself, as he did four years ago. Last time around, he thought he could help build up the Reform Party. This time around, he's less sanguine. "Why do it if all you're going to do is elect John Kerry?" he asks. So, despite two-plus years of polemicizing against the president in his magazine, Buchanan sees nowhere else to go in November.

Thomas Fleming, president of the paleocon Rockford Institute and editor of its magazine, Chronicles, is with Buchanan vis-à-vis Kerry. But unlike his fellow paleocon, Fleming says that there is a "less than zero" chance of him voting for Bush. "You can't let Kerry's obnoxious qualities persuade you that Bush is somehow the lesser of two evils," he says.

Whom does that leave? Fleming says that he's "probably the only conservative in the world who's considering voting for Ralph Nader, who is "passionately sincere" and "patriotic in a way the Republicans are not." (Though Buchanan is unlikely to vote for Nader, he is sympathetic to the independent candidate. "Ralph's good," he says, "on trade and on the war. ... I hope Ralph does well.")

Walt disagrees with Preble that the two candidates are indistinguishable on foreign policy. "There are real, sharp differences," he says, "in the way the country is going to move under a Kerry presidency. I might not think it was perfect, but I can't imagine it wouldn't be better."

[This article originally misidentified John Hulsman as a signatory to the Coalition for a Realistic Foreign Policy.]