There are various tests for winning US presidential elections: the economy; likeability; double letters.  But a key factor seems to be having an unnaturally full head of hair.  Americans just don’t like bald presidents, if they have a choice.

Kennedy, Carter, Reagan, and Clinton all had spectacular manes.  Nixon looked better than Humphrey.  Johnson/Goldwater and Eisenhower/Stevenson were tossups.

In recent years the Democrats obviously overestimated the hair factor.  Dukakis’ and Kerry’s big hair did them little good.  Just to be safe, though, Obama had better ease off on the razor, just enough to overshadow McCain’s combover.