I’m in Des Moines today and tonight, reporting live from Drake University, where the first Republican presidential debate with Newt Gingrich as a front-runner will take place at 9 pm ET tonight on ABC.  The debate will be moderated by Diane Sawyer and George Stephanopoulos, but the real question will be whether and how hard each of the other candidates will go after Gingrich in an attempt to damage his momentum.  That pattern has repeated itself with the other boomlet candidates, but the other boomlet candidates didn’t have Gingrich’s talent for debate.  Will they shy away from direct attacks tonight, and if they do attack, how will Gingrich respond?  I’ll preview the stakes for each of the candidates tonight:

• Newt Gingrich — Welcome to the top spot, Mr. Speaker.  Gingrich might not get attacked by every candidate on the stage, but he’s going to take some heat from at least some of them, with Michele Bachmann and Rick Santorum the most likely to go on offense. He needs to avoid responding too harshly to their criticisms and eroding the Newt 2.0 statesmanlike image he’s successfully created in the last few months.  His command of detail and policy will make him a formidable opponent, and he’s likely to come out the winner in most exchanges tonight.  If he can focus his own attacks on Barack Obama while parrying those from his competitors on stage, he’s going to sail through the debate tonight.
• Mitt Romney — Romney needs to slow Gingrich’s momentum, but be careful about coming off second place in an exchange with Gingrich.  Remember that Romney has bested Gingrich in a debate exchange before — the only candidate to do so — but Romney has plenty of his own vulnerabilities that Gingrich can expose, too — especially the fact that the surrogate Romney tasked with attacking Gingrich’s conservative credentials played a big role in Bush 41’s “read my lips” reversal.  I’d expect any attacks from Romney to be more oblique, focusing on his own expertise and subtly making the comparison.  Besides, it’s almost certain that other candidates will do the attacking for Romney — just as they did when Rick Perry jumped into the race, which brings us to …
• Rick Perry — Perry has just thrown a bunch of ad money into Iowa, with the idea that he could still rally social conservatives to his side and away from Gingrich.  Perry has been terrible at delivering debate attacks, though, and engaging Gingrich could be political suicide if Perry doesn’t have absolute command of the facts.  I’d expect Perry to focus on presenting himself in a completely positive light and hope that others will pick up the attacks instead, in a sense drafting behind Romney.
• Ron Paul — Paul won’t be intimidated by Gingrich, and it’s a certainty that he will spend time going after Gingrich on a number of fronts.  His poll numbers in Iowa have also risen, and he could benefit from any Gingrich decline, but even more than that, it’s in Paul’s nature to attack the Republican establishment.  He’ll probably go after Romney too, and perhaps everyone else on stage.  If he comes off the worst in an exchange, it won’t really matter to Paul’s supporters, nor to Paul himself.
• Michele Bachmann — Expect Bachmann to go after Gingrich on social-conservative issues.  She’s well-versed on those, and like Perry, sees social conservatives in Iowa as the path to winning the caucuses.  If she can do so without tipping over into hyperbole and personal attacks — no more Government Needle scaremongering — Bachmann could be very effective tonight in giving social conservatives a reason to rethink Gingrich.
• Rick Santorum — Everything that I wrote about Bachmann applies to Santorum as well, although he doesn’t have the personal connection of Bachmann to Iowa social conservatives.  Santorum doesn’t have the credibility issues that Bachmann sometimes creates for herself, but he has to deliver his attacks in more measured tones, sounding more statesmanlike than annoyed or frustrated.

Two candidates won’t appear in tonight’s debate.  Herman Cain suspended his campaign and will likely announce an endorsement in the near future.  Jon Huntsman will conduct a townhall in New Hampshire, having not met the threshold of polling support in Iowa to participate tonight.

Before tonight’s debate, several of the candidates will attend a forum sponsored by Veterans for a Strong America.  I’ll also be there, and hope to have video and first-hand reporting from the event later this afternoon.  Stay tuned.