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."