02/22/2012 11:12 pm ET Updated Apr 23, 2012

Final Four: The GOP Arizona Debate

Scorpions in a bottle, or comrades in arms? The GOP presidential debate in Mesa, Arizona, was really two separate events: a first half in which the candidates spat venom at each other, and a second half in which they agreed on most everything -- all except contrarian Ron Paul. The net result: a debate that probably did not alter the chessboard, even as it generated a fair amount of sparks.

Of the four contenders, Rick Santorum had the best night. It has taken him twenty debates, but Santorum finally ended up with the primo onstage real estate, right next to Mitt Romney at the heart of the action. Santorum basked in his newfound position of strength, as though he ought to have been occupying center stage all along. From a visual standpoint this allowed Santorum to dominate the telecast, up to and including the shots in which he was listening and not talking.

As a debater Rick Santorum is far from perfect. Too often his answers become convoluted, and there's an immaturity about the man that undermines the seriousness of his claim on the White House. But Santorum's earnestness never fails him, and there's no denying that he has the gift of authenticity. More than his rival Republicans, Santorum appears to have learned from the experience of participating in so many joint appearances with his opponents -- he is that rare candidate who is more effective in debates than on the stump. His debate performances keep getting better, even as the others seem to be marking time.

Mitt Romney delivered another technically competent performance, although at times he looked tired. In his back-and-forths with Santorum, Romney mostly held his own, but he never quite managed to dispatch his rival the way he did Newt Gingrich in Florida. Romney suffered a particularly bad moment at the end of the debate, when he lapsed into an uninspiring closing statement rather than answering moderator John King's wrap-up question: What is the greatest misconception people have about you? Instead of playing along, Romney snapped at King for trying to bring him back on course: "You get to ask the questions you want, I get to give the answers I want." If Mesa ends up being the final Republican debate of the season, no one will be happier than Mitt Romney.

Newt Gingrich, who increasingly resembles the character actor Sydney Greenstreet, had his moments in the spotlight, but at this point in the campaign his statements have taken on an air of irrelevance. Ron Paul likewise had a solid debate that ultimately won't matter much.

Nobody was terrible in this debate. It is obvious why these candidates advanced to the final four -- and just in case we needed a reminder, there sat Rick Perry in the audience next to Callista Gingrich. Rick Santorum may have done himself some good in Mesa, and Mitt Romney did himself no harm. When scorpions in a bottle start agreeing with each other, you can only call it a draw.