As I always say, to judge a candidate's performance you need to consider what they were trying to accomplish. Tonight was the start of what will surely be a series of engagements in which Mitt Romney and Rick Perry battle for the Republican Presidential nomination. As I see it: Republican voters probably like Perry better, but may think that Romney is the better bet against Obama. If Romney can get those voters -- beginning with the elites/establishment and working down to the rank-and-file -- to feel stronger about the second half of that equation than the first, he wins. If Perry can keep them feeling stronger about the first than the second, he wins.
I thought they both did pretty well. Romney has to feel that his solid performance -- and more importantly, Perry's criticism of Social Security and weak performance on foreign policy -- pushed some Republicans toward the 'maybe we need Romney in the general' side of their inner dial. Perry has to feel that his solid toe-to-toe standing up to Romney in the early exchanges, and his crowd-pleasing feistiness -- like his call for more provocative language, and his defense of the death penalty, moved some dials the other way.
In other words, no major change -- which I'd say is a slight victory to Perry, because I think without a shift at some point between now and January, Perry's the nominee.
There were, incidentally, quite a few other candidates on the stage, which is good for the entertainment value. Michele Bachmann, who needed to somehow insert herself back into the race, was instead almost invisible. Herman Cain -- remember when he was momentarily a candidate? -- has worn thin with his vaguem uninformed prescription of fixing whatever it is we're talking about. He did nearly get the "didn't see that coming" line of the night for saying we should base our Social Security program on the Chilean example, but Ron Paul topped him with his call to stop paying for air conditioning for our troops in Iraq and Afghanistan.
Speaking of Paul, his goal in these debates, I've always thought, is to do enough to please his following, without going far enough to demonstrate how completely unelectable he is. But Brian Williams clearly had a contrary goal, of pressing Paul to defend true, diehard libertarianism -- and Paul just can't help himself. (Also, the way he accused TSA agents of "sexual activity" came off a little creepy-perv-from-Family-Guy.)
Rick Santorum is irrelevant at this point. Newt Gingrich is not going to win back any voters, regardless of his bluster. And Jon Huntsman is fine, and did a reasonably good job of debating, but he has pretty much zero to do with the Republican nomination process.
Mind you, one or more of those secondary candidates might become relevant if either Romney or Perry completely disintegrates. And I suppose it was possible that Perry would, in his big national debut. But clearly those are the big two, and they're going to go quite a few rounds with each other between now and early 2012.