This was the night in which the conservative closed information feedback loop and its close cousin, lazy mendacity, caught up with Republican presidential nominee Mitt Romney — in a big way.

The topic was Libya. It’s an issue that should work well for the challenger; surely at the very least, Barack Obama’s administration had a tragedy on its hands, one that might have been preventable, and one that most seem to think Obama and his administration have handled poorly after the fact. There would seem to be a variety of attacks available. Was Obama’s Libya intervention a mistake? Was there something about the Libya attacks that undermined Obama’s claim of policy competency? Obama’s handling of the Arab Spring? Romney had to think himself lucky when the only foreign policy question of the night was on this topic, teed up perfectly for him.

Yet Romney drifted first to an attack on Obama for going to a fundraiser, and then wandered around the Middle East to little effect, then finished his first pass at the question with the mythical “apology tour” and his recent empty rhetoric about an “unraveling” policy.

And then it got worse. Obama lectured Romney for daring to accuse him of playing politics with the issue. The truth is, he supplied an opening for Romney; a candidate who knew what he was talking about could have pointed out that of course in the United States, these things become political issues.

Instead, Romney ignored that part of it, and clung to — and repeated — a conservative talking point about just exactly when Obama had called the attacks “terrorism,” a talking point that has the twin advantages of being both pointless and factually incorrect.

As Candy Crowley broke in and confirmed. Or at least the factually incorrect part of it. The exchange, as a whole, just seemed awful for the challenger.

The question is: Why did this portion of the debate go wrong for Romney?

Romney has been doing this for, literally, years now. His main platform on foreign policy, after all, is to reject an “apology tour” that never happened and that people have been correcting him on for years. He’s come up with the new one, “unraveling,” recently, but hasn’t bothered to fill in anything — at all — about what is unraveling, or how. Nor is it just foreign policy. His tax plan doesn’t come close to adding up, and his jobs plan doesn’t, either. He repeats flat-out lies again and again, no matter how many times they’ve been shot down. As I said, lazy mendacity — even where the facts would do well for him, as in trillion-dollar deficits, he chooses instead to constantly claim that Obama doubled the deficit, which isn’t true. Sure, every candidate exaggerates and stretches and spins, but Romney’s complete apparent indifference to bother to get things right is unusual.

The question is: Why shouldn’t he do it? Republican-aligned media surely aren’t going to call him on it. Indeed, within the GOP political loop, there’s no one who is even going to realize that they have a basic factual thing wrong; that’s what happens when you convince yourself that the neutral press is out to get you, and you’ve trained your supporters to only pay attention to what they hear on Fox News and the Rush Limbaugh program, so you had better stay tuned to them yourself or else you won’t be able to talk the way you need to. Of course, that’s how a candidate winds up insulting half of America, because that’s what high-level party donors expect to hear.

And as I’ve argued, that’s also how a campaign winds up with lazy mendacity; if all it cares about is a thoroughly uncritical press, then why should it bother to back up assertions that will never, within the loop, be challenged?

Now: I have no idea what effect, if any, tonight’s debate will have on undecided voters (which, to be sure, depends to a great deal on how the press scores it, which clips get replayed, which headlines are deployed). So I don’t want to claim that Romney’s problems with the Libya question will “matter” in that sense. But I’ll say what I always say about it: The closed information loop leaves conservatives vulnerable, and it makes it very difficult for them to govern effectively when they are in office. I think anyone watching tonight saw why.