Jeff Jacoby
Men and women differ in countless ways, from their interest in sports to their views on gun control to how rare they prefer their hamburgers. It's no revelation that there are discrepancies in their voting habits too: Democratic candidates tend to get more support from women voters, Republicans do better among men. This is the vaunted "gender gap,"which has been a staple of presidential campaign coverage for at least three decades.

For some reason the notion took hold early on that this divergence would be a boon for liberals. "The gender gap is the Grand Canyon of American politics," exulted Democratic strategist Ann Lewis in 1983. "It is wide, it is deep, and it is beautiful." But that was wishful thinking: Of the last eight presidential elections Democrats have only won three. The gender gap is real; it just doesn't affect much.

Far more potent is the marriage gap in American politics. Married voters tilt Republican, while single voters favor Democrats. Back in 2004, USA Today advised readers of an easy way to predict whether a woman intended to vote for Kerry or George W. Bush: "Look at her ring finger." Today that's an even better rule of thumb.

A Quinnipiac University poll
this month suggests just how important the marriage gap has become to President Obama's reelection hopes. Among voters nationwide, it found, Obama's advantage over Mitt Romney is narrow, 46 percent to 43 percent. Drill beneath the surface, however, and a sharp divide appears. Among married voters, Romney has a robust 13-point lead, 51 percent to 38 percent. But Obama enjoys an even larger lead among singles, 54 percent to 34 percent. Unmarried women in particular are in the president's camp: They support him 2-1 over Romney.

Jeff Jacoby

Jeff Jacoby is an Op-Ed writer for the Boston Globe, a radio political commentator, and a contributing columnist for