8 p.m. ET on CNN. There’s another debate tentatively scheduled for March 19 on PBS, but if Romney holds on in Michigan and then does well on Super Tuesday, he’ll have no incentive to participate and PBS will have no incentive to air it without him. So this is, in all likelihood, it: The last chance for Santorum to make the case against RomneyCare, the last chance for Romney to convince Republican voters that they’re better off with him for whatever reason, and the last chance for Gingrich to manufacture a poll bounce by grandstanding with the moderators. John King, his old nemesis, is back tonight, but a Gingrich campaign source says they’re eyeing this as an opportunity for him to seem “statesmanlike” while Romney and Santorum maul each other. Other Gingrich advisors tell the NYT that he needs to attack. Who’ll show, Good Newt or Bad Newt? Either way, Gingrich will have to focus on Santorum to try to reposition himself as the conservative alternative to Romney. You know who that benefits?

Two subplots tonight. One: Are Romney and Ron Paul quietly coordinating against Santorum and Gingrich? And if so, what’s Paul getting from Romney to do that? Go read Matt Lewis for an unlikely but irresistible theory on that. Two: How much time will be spent picking through Santorum’s rhetoric on contraception and other cultural hot buttons? His campaign team gently reminded the media today that most Americans share his belief in Satan, but it’s not the theological material that’s most problematic for him. The NYT notices a trend I’ve mentioned before:

The latest poll, conducted in Arizona by NBC News/Marist and released Wednesday, showed that women support Mr. Romney over Mr. Santourm 46 percent to 23 percent. In addition, Mr. Romney has an eight percentage point lead among men.

Some Democrats and others have criticized recent remarks by Mr. Santorum about barring women from combat roles in the military, and his personal disapproval of birth control. The latest polls may be showing the first signs that Mr. Santorum is alienating women — including Republicans — with some of his views.

A separate poll in Michigan by NBC News/Marist showed far less of a gender gap between the front-runners, but there was still a slight divide. Men were evenly split between the two top candidates, but 39 percent of women went for Mr. Romney to 33 percent for Mr. Santorum, a former Pennsylvania senator.

Nationally, Santorum’s numbers with women have vastly improved so I don’t know how to explain the gender gap in Michigan and, especially, Arizona. Can’t wait to see whether Romney tries to exploit it, though. Does he dare challenge Sweater Vest from the left on cultural issues given how skeptical the base already is about Mitt’s conservative bona fides?

Here’s the Hot Air/Townhall widget for livetweeting during the debate. Exit quotation from Haley Barbour: “It is not accurate to say that a hotly contested convention is necessarily bad. I am not saying it is necessarily good, but I don’t think it is accurate to say it is necessarily bad. Let’s just see.”

Update: Here’s CNN.com’s livefeed in case you’re stuck without a TV.