One is that, while the presidency offers countless political advantages, it does trap its occupant in a bubble of prestige and security that is impossible to avoid. The bubble is especially dangerous in hard economic times, when voters are on watch for politicians who may not be aware of their day-to-day hardships. The notion that George H.W. Bush hadn’t set foot in a supermarket in years was deadly (even if it was inaccurate). George W. Bush’s modest support collapsed for good at almost this precise moment in 2005; and even before then, W suffered steady criticism that he was insulated from bad news about the Iraq War. And God forbid the commander in chief should suffer some dignity-shredding humiliation like, say, a freak rabbit attack.

The second is that stereotypes die hard in politics, and certain attacks are more effective against one party than against the other. Romney may be even more of a Harvard man than Obama is. But he knows that Americans are probably more inclined to think of Democrats as the party of know-it-all academic elites. (It helps that Obama was actually a professor.) In fact, anti-elitism has been a crucial GOP line of attack in every recent election; never mind that in each case the substantive difference was almost nonexistent. In 2000, George W. Bush–Yale and Harvard man, son of a President–mocked Al Gore as a snooty elitist. Four years later, Bush’s team taunted Vietnam vet John Kerry as a windsurfing, snow-skiing dilettante (never mind that Air Force reservist W. rode a $2300 bike, among other things). John McCain, he of the multiple houses and a half-lifetime in the U.S. Senate, cast himself as Joe the Plumber’s champion against the celebrity professor Obama.