While Obama usually likes to triangulate himself rhetorically between realism and idealism, "realist" is the label his biggest fans in the foreign policy establishment use most. "Obama is a realist, by temperament, learning and instinct," Fareed Zakaria wrote in Newsweek in 2009. "More than any president since Richard Nixon, he has focused on defining American interests carefully, providing the resources to achieve them, and keeping his eyes on the prize." More recently, Harvard's realist guru, Stephen Walt, saluted Obama's "buck-passing" as a feature rather than a bug of his realist foreign policy.
Among the many problems with realism is the fact that it sits on a tower of questions. Realists say we should do only what is in our national interest rather than pursue ideological goals. But what is our national interest? Nearly every so-called realist position is in fact ideological from someone else's perspective. And pretty much every ideological position can be defended in terms of the national interest. The realist's answer to this pickle is to be so smart that you can always know what's in the national interest at every moment.
Except nobody is that smart. During a crisis, the temptation is always to sacrifice the idealistic to the demands of the moment, i.e., to be a buck-passer. Why create problems by supporting this dissident or condemning that stolen election? Why make a ruckus about freedom of the press or the rule of law? Why honor this inconvenient treaty when we have so much to gain from trade with our ally's enemies? Save the idealism for later.
That's the process that kept Mubarak in power for 30 years. It's also the process that, over time, leads to everyone hating you, because no one trusts you. Just ask the Egyptians.