Tonight’s debate will once again provide a critical moment for two of the three top contenders in the Republican nomination.  This will be the first comprehensive policy debate for Herman Cain as a frontrunner, after performing impressively in the economics debate last week.  For Rick Perry, though, this may very well be his last opportunity to demonstrate enough skill in presentation and communication to get some of his initial supporters back on his bandwagon.  Byron York reports that the Texas governor’s team has a new strategy to get Perry more involved — and more eloquent:

 “We’re going to pay a little less attention to the rules,” says a source in the Perry camp who asked to go unnamed.  “One of the things the governor tried to do in New Hampshire [at the Bloomberg/Washington Post debate] was to live by the time limits set by organizers.  No one else did.  As a result, one could view the governor’s performance as having less to say, when in fact he was simply trying to live up to the rules of the debate.  They’ve rarely been enforced, and we’re not going to pay much attention to them.”

A number of observers remarked that Perry seemed to check out of the New Hampshire debate for long periods of time.  Whatever the explanation — whether he was trying to abide by the rules or simply wasn’t engaged in the conversation — it appears Perry will try to take a more active role in Las Vegas.

Was that really the problem?  The rules seemed to be generally followed except for Rick Santorum, and the result of the debate didn’t do much for his polling in the past week.  Perry didn’t get a lot of questions last time, but when he did, he didn’t take advantage of the allotted time anyway.  When pressed for his plan on economics — in a debate that had been announced as an economics-only forum — Perry averred, saying that he needed more time to produce a plan after having been in the race for two months.  He then offered a strange assertion that policy didn’t matter, but that what mattered was getting the economy back on track … which was the point of discussing the economic plans in the first place.

The economy will obviously be a key topic in tonight’s debate, and now Perry has rolled out his own plan, which gives him some specifics to present.  Whether or not he can recover his mojo will depend on how he presents them — and more importantly, how he defends them.  Most of Perry’s problems have come when other Republicans go on the attack, which seems to derail Perry’s efforts.  Nowhere has that been more true than on immigration, where Perry’s “heartless” accusation enraged the very base he had been trying to court.  Perhaps he can point to a recent Washington Post article which detailed the use of a “small army” that Perry has deployed on the border to engage the cartels.  The tone of the report is clearly not sympathetic to Perry, but he can at least use it to argue that he alone among the candidates has actually done something about illegal border crossings.

Perry needs a big, positive performance in tonight’s debate in order to change minds about his prospects and recover some of his standing in the party.  What about the rest of the field?  Let’s start with the other hot-seat candidate, Herman Cain.  Cain answered questions about his ability to handle attacks on stage, as well as his ability to command attention.  Now he needs to demonstrate that he’s been doing some homework on foreign affairs.  Earlier this year, Cain slipped on a rather routine question about the Palestinian demand for a right of return, exposing a potentially game-ending gap on foreign policy.  Cain claimed on Sunday to have been studying the writings of John Bolton and Henry Kissinger and to having informal conversations with Bolton as well.  If so, this is pop-quiz time, as Cain will surely get challenged by Rick Santorum on foreign policy, and perhaps — maybe — Mitt Romney as well.  If Cain can’t answer another basic foreign-policy question on the fly, he’s going to damage his momentum.  If he handles it well, his credibility will continue to rise, and Romney will have a big problem on his hands.

Romney’s task is still pretty simple: stick to what has worked all along.  Act like the frontrunner and don’t engage the second tier.  Romney has a significant amount of strength on foreign policy, but he may have more trouble if talk turns to environmental policy.  If candidates paid attention this week, they could hit Romney for his partnership with John Holdren and appointment of Douglas Foy, especially when it comes to regulatory adventurism.  Romeny’s going to be prepared for those questions, but getting them aired might be enough to damage his calm somewhat.  Still, Romney has all but secured his status as a front runner through these debates by projecting an image of cool confidence and competence, and as long as he manages to continue doing that, he’ll have a leading position when the primaries begin.

For the rest of the field, the mission will be to find a way to replace Herman Cain as the so-called “flavor of the month.”  Michele Bachmann has already blown momentum and probably can’t win it back, and Jon Huntsman keeps attempting to use tone-deaf jokes that fall utterly flat.  Santorum needs to find ways to respond and attack without sounding petulant and angry.  Ron Paul will impress his base, but no one else will be convinced, especially when his inevitable reaction to the Iranian plot will be that it’s really our fault.

Of all the other candidates on the stage, Newt Gingrich might be the one to watch.  He has slowly gained momentum by being among the most positive on stage (except to moderators) and demonstrating his encyclopedic knowledge and quick wit.  If it wasn’t for his personal baggage, he might already be the front-runner — and if both Cain and Perry stumble late, Republicans might be inclined to take on his baggage rather than hand Mitt Romney the nomination virtually unchallenged.