The full clip won’t be available until tomorrow but we all know how it’s going to go, so the two items here should tide you over. I’m not one of the people who believes, counterintuitively, that last night’s atomic gaffe will end up helping his campaign, but I do understand their logic. Perry’s never been more sympathetic than he is right now: We’ve all suffered that same form of vapor lock and he’s been a gamer today in doing damage control by determinedly making fun of himself for it. (He’ll swing by Jon Stewart’s show after taping Letterman to be flogged for his sins there too.) The problem is, likability was never Perry’s problem. If it was, as it is with Romney, this comedy tour would do him a world of good. His problem is that he consistently seems not ready for primetime and none of the self-deprecation undoes that. Jonah Goldberg:

[P]ut aside the queasy awkwardness of the moment for a second. Perry couldn’t remember that he wants to shut down the Department of Energy!? For weeks, energy reform was the only substantive policy he’d put forward. Energy is still one of the only topics he can discuss with anything approaching fluency. But he couldn’t remember he wanted to shut down DOE? It’d be more understandable if he forgot the Department of Commerce — people forget the existence of the Commerce Department all of the time.

Last, and this is a point a lot of people are making, but it’s an important one. His performance last night confirmed — with an exclamation point — the negative narrative of his entire campaign. Everyone could forgive Ron Paul if he spaced out on the name of a cabinet agency he wanted to shutter, because everyone knows that Ron Paul knows what he knows and has no problem explaining himself under normal circumstances. People are much more unsure about Perry and he compounded that uncertainty last night. It’s fine to say everyone has these bad moments. That’s true. Everyone makes mistakes. What you look for are patterns. Last night was so deadly because Perry reinforced his pattern rather than deviated from it. And he was already on borrowed time.

Exactly. Campaigns are all about narratives, and the Perry narrative since virtually the first debate is that he’s never quite sure what he’s talking about unless he’s talking about Texas. Last night was the exclamation point. Over at the Examiner, Byron York attributes that to two probably fatal weaknesses:

The first is that Perry, for all his success as governor of Texas, appears not to have thought long and hard about why he wants to be president and what he would do if he achieved his goal. It’s the kind of intense thinking that goes on long before a campaign actually starts; once the candidate is on the trail, it’s too late for soul-searching, self-evaluation, and in-depth study. It’s hard for a candidate to have a firm grounding in issues and policy if he has not first done that kind of thinking.

The second reason is that since Perry made the decision to run for president — jumping in at the late date of August 13 — he has not done much of the kind of day-in, day-out, speaking-six-times-a-day campaigning that gives candidates the ability to repeat their positions extemporaneously, backward and forward, and sometimes in their sleep.

Look at Perry’s public schedule for the last month. It was plenty busy, but it wasn’t filled with the town halls and question-and-answer sessions that allow candidates to hone their message.

To some extent, Romney’s also guilty of those charges. He does do Q&A’s with voters, but he’s famously avoided the extended interview format of the Sunday morning chat shows because he doesn’t want to be quizzed on flip-flops for any length of time. I get no sense from him that he’s thought long and hard about why he wants to be president either, merely that he does want to be president — badly enough that he’ll say whatever he has to in order to win. It’s the intensity of that ambition, I think, that most keenly separates him from Perry. It’s impossible to imagine Romney spacing at a debate because we all assume he practices his answers for hours and hours and hours on end in the interest of winning. Perry seems more inclined to trust his gut and his track record of victory in Texas: He practices, I’m sure, but not like the robo-frontrunner does. Last night, when he went to the mental script, it just wasn’t there when he needed it. And now even Newt’s making fun of him for it.

Here’s the Letterman clip plus more damage control with Megyn Kelly this afternoon. He does a good job with the top ten, but there’s a lot of pathos in seeing him forced to stoop to this after he rode into the race three months ago as the conservative savior. Out: Rick Perry. In: Rupert Pupkin? Exit question via Nate Silver: Should he go for broke now in Iowa? He’s reached the point poll-wise where, if he doesn’t win there, he’s basically finished.