The simplest explanation for Cantor’s defeat

House Majority Leader Eric Cantor is toast. In an unprecedented upset that nobody foresaw, the House majority leader was defeated last night when 36,000 of his 758,000 constituents voted for Tea Party candidate David Brat in the Republican primary. A House Majority Leader hasn't lost in a primary since they created the position in 1899, so commentators are now scrambling to analyze what Cantor's loss says about American politics, but the explanation for what happened is much smaller than the event itself.