Maggie Gallagher

In Alabama, among those who say the top quality they want in a candidate is someone who "can defeat Obama," Santorum lost 51 percent to 15 percent.

In Mississippi, 39 percent chose 'can defeat Obama' as the most important quality in a candidate, and these broke heavily as well for Romney, 46 percent to 22 percent.

Santorum has a real opening to explode the myth that Romney is the most electable candidate. Romney has revealed himself to be a front-runner with clay feet, running inside a glass house built on sand.

A third thing keeping Romney in the race? The argument made from despair, aka 'inevitability.'

All of these are very weak ground on which to stand for a presidential candidate who hopes to defeat Barack Obama in November.

Maggie Gallagher

Maggie Gallagher is a nationally syndicated columnist, a leading voice in the new marriage movement and co-author of The Case for Marriage: Why Married People Are Happier, Healthier, and Better Off Financially.