The artillery fire begins at 9 p.m. ET on ABC and, after an overnight ceasefire, resumes bright and early tomorrow at … 9 a.m. Really. Note, though, that the second debate won’t air live on NBC but rather in your regular local time slot for “Meet the Press.” If you’re recording it, look for it then.

Back-to-back debates presents an interesting strategic question for the Not Romneys. Should they use both forums as an opportunity to pile on Mitt in hopes of dragging him back to earth or should they use one debate to beat on Romney and the other to distinguish themselves from each other? Even at this late date, they still need to define themselves: Apparently, a not insignificant chunk of New Hampshirites was surprised to learn this week that Rick Santorum is against gay marriage. Besides, now that the new polls have showed Romney’s huge lead in NH holding up after Iowa, the calculus has changed for the rest of field. Instead of trying to pull the upset, they’re really trying to place second and then tout that in South Carolina as proof that they’ve been crowned the sole remaining viable alternative to Mitt. So while Romney will take his licks this weekend, (a) Santorum and Ron Paul will hammer each other in hopes of locking up second; (b) Paul and Huntsman will hammer each other in a mini-battle for independents and liberals; and (c) Perry will hammer Santorum in order to kill his momentum before SC and clear the way for a second look at Texas. (Aside: Why is Perry participating in these debates?) The only guy out there who’s likely to train all of his fire on Romney is — well, you know:

With two debates 10 hours apart this weekend, Good Newt versus Bad Newt will be one of the most compelling subplots. It’s clear he hasn’t totally decided which approach to take yet, and even if he does aim to tone it down, it’s not clear he has the discipline to do so…

“He was ‘the ideas guy’ until three weeks ago, when he became a process guy,” said one veteran GOP strategist, who is neutral in the race. “Now all he talks about is process, polling, negative ads, gross ratings points. He has no campaign. He has a moving think tank. The psychology that’s going on is, he thought he was going to win. And he’s devastated with what happened to him and he can’t quite comprehend it. He’s just fuming inside. He can’t believe it happened to him.”

The best window into Gingrich’s state of mind on the eve of the debate may be this Newsweek piece reporting that his Super PAC is set to roll out a 27-minute video savaging Romney for the layoffs at companies acquired by Bain Capital. Actual quote from the narration: “A story of greed. Playing the system for a quick buck. A group of corporate raiders, led by Mitt Romney. More ruthless than Wall Street. For tens of thousands of Americans, the suffering began when Mitt Romney came to town.” Go look at the webpage that the Super PAC has set up to showcase the video. See now why I’m using artillery metaphors for tonight? I don’t know why Newt would go this route after the heat he took on the right for his earlier jab at Mitt’s Bain earnings; it’ll alienate plenty of conservatives, in part because it’s precisely the sort of attack Obama’s preparing for Romney as part of his big class-warfare election strategy. But maybe Newt doesn’t care anymore. Maybe damaging Romney is more important to him now than winning. Or maybe he’s worried about Santorum’s blue-collar appeal to white working-class voters in the Republican base and figures he can kill two birds with one stone this way, positioning himself as the true blue-collar champion against white-collar demon Mitt Romney. (Added bonus: If Newt somehow won the nomination this way, it would partly neutralize Obama’s strategy in the general.) Cynical, yet effective. Maybe?

Here’s the Hot Air/Townhall Twitter widget. Ed will be updating live from the debate. One other thing to keep an eye on: Will Santorum go after Newt? He’d rather focus on Romney but he can’t afford to finish behind Gingrich in NH. That would fuel a “Newt comeback/Santorum fade” narrative before South Carolina, where Newt’s still reasonably strong, and that would probably finish Santorum off. And because Gingrich always does well at the debates, he’s probably bound to get some sort of bounce after this weekend anyway. Santorum might have no choice but to attack.