AP Photo

After nine months on the periphery of the Republican race, tonight’s debate in Mesa, Arizona, was Rick Santorum’s opportunity to show he deserved to be considered a frontrunner. But instead of using the occasion to build on the surge that led him to the top of the national polls, the former senator flopped as Mitt Romney and Ron Paul pounded him unmercifully from the start of the evening to its finish. By the end of the night, the grim look on his face betrayed the effect of having to explain his stands on issues such as earmarks, being a “team player” in the Senate and his support for Arlen Specter and “No Child Left Behind.” Whereas in previous debates, he had been on the attack pointing out Romney’s inconsistencies, in Mesa, it was his turn...