I'm sorry I missed this earlier. Walter Russell Mead gives a name to a disease infecting some so-called foreign-policy realists: Israel Lobby Syndrome:

Now in case any of my readers have missed the census news since 1790, there are not now and never have been all that many Jews in the United States.  Less than two percent of the roughly 300 million people in the United States are Jewish.  This means that Jews can at most account for two of that 63 percent of the population who sympathize with Israel.  Pro-Israel gentiles in America outnumber pro-Israel Jews by a factor of 20-1, and ever since polling on this issue began, the overwhelming majority of the Americans who support Israel against its enemies haven't been Jewish.

This brings us to a problem: why do so many people, especially self-described 'realists' when it comes to Middle East policy, find it mysterious that American foreign policy supports Israel?  Surely in a democratic republic, when policy over a long period of time tracks with public sentiment, there is very little to explain.  American politicians vote for pro-Israel policies because that is what voters want them to do.  Case closed, I would think.  Late breaking news flash: water runs downhill.

Yet many otherwise intelligent people are drawn over and over again to the idea that a mysteriously powerful Jewish lobby is somehow thwarting democracy to bend American foreign policy to its nefarious will.  Polls, reason, history, none of this matters.  America supports Israel because of 'the Jews'.