I’ll be curious if Romney attacks the complete lack of credibility in Pawlenty’s economic plan. (Check out the takedowns of Pawlentynomics by Ezra Klein, Ruth Marcus and The Post’s editorial board.) I’ll also be curious if Pawlenty gets tough questions about the proposal, as he should. Pawlenty has moved so far to the economic right with this proposal that he makes Paul Ryan look like a social democrat. (Yes, really.) But it will be tricky for Romney, because at some level he would have to challenging Pawlenty’s plan from “the left” by saying it is unrealistic about how much it’s possible to shrink government. Pawlenty is also unrealistic about future economic growth, but it never goes down well when a candidate plays the pessimist’s role.

      Watch to see if either challenges the other’s record as governor. Oh, yes, Pawlenty will attack the health-care mandate in Romney’s Massachusetts health plan. In fact, he started already on “Fox News Sunday.” “President Obama said that he designed Obamacare after Romneycare and basically made it Obamneycare,” Pawlenty said. “What I don’t understand is that they both continue to defend it.” Obamneycare – nice touch.

     But does Pawlenty go beyond that? Democrats have been circulating numbers showing that Massachusetts ranked relatively low among the states in job creation when Romney was governor. Does Pawlenty go after that? Will Romney go after aspects of Pawlenty’s record in Minnesota?

      And both will have to be careful, because if they spend the next few months tearing at each other, former Utah governorJon Huntsman could be the beneficiary. (He’s skipping this debate, which, by the way, is sponsored by CNN, WMUR and the Manchester Union-Leader.) Huntsman is the third man seeking votes from the non-far-right part of the GOP.  Does he lose by skipping this debate? Maybe. But he also may gain by helping encourage the Romney-Pawlenty attack dynamic.

       Then there will be Newt Gingrich vs. Newt Gingrich. This debate is huge for Newt. He has to dominate, and it’s very hard to dominate a multi-candidate debate. He’ll also have to explain why his campaign fell apart. His claim is that he’s sufficiently interesting and compelling that he can run something other than a conventional campaign. He’ll have to prove it tonight. With so many political types (including many Republicans) ready to bury his candidacy – if they haven’t buried it already – he needs an exceptional performance.

       Then there’s the right-wing debate: Michele Bachmann, Ron Paul, Herman Cain and Rick Santorum. Bachmann has been getting the most press and she seems the best positioned of the right-wing candidates for the Iowa caucuses. She needs to outshine all the others, particularly Cain, the Godfather Pizza entrepreneur who is doing far better in the polls than anyone imagined. Paul is always interesting as the pure libertarian. He has a rock-solid base, but can he move beyond it? Santorum will almost certainly benefit from this debate. Expectations of him aren’t high, but he’s more seasoned than the rest of this group.

        Oh, yes, and I hope to see a Bachmann-Pawlenty debate. Why is Bachmann challenging her state’s former governor? What going on between these two Minnesotans? Maybe we’ll learn a bit about this rivalry.

      There will be the everyone-else-against-Romney debate. He is unquestionably the front-runner in New Hampshire. All these candidates have an interest in bringing him down. Do they all go after him? Does this rattle him or does he look good as the victim of a mass attack – assuming there is a mass attack? With his usual brio, The Post’s Greg Sargent casts the question this way: “Has Mitt Romney’s relentless focus on the economy and his new turnaround whiz-kid act really cemented true front-runner status? Or is it only a matter of time until T-Paw and other opponents succeed in awakening GOP primary voters to the transparent phoniness of Romney’s conservative rhetoric and his previous embrace of sensible positions on climate change and the individual mandate, dooming him in a state he must win?”

      There are two other contests here. The whole crowd will be attacking President Obama again and again and again. How effective will these attacks be? Who sounds like the most effective opponent? Whose criticisms have the best chance of appealing beyond the Republican base? And how well does the Democrats’ instant response team take apart the criticisms? Yes, this will be an early test of the Obama campaign apparatus, too.

      Finally, there’s CNN vs. Fox News. At the 8 o’clock hour, this debate is up against Bill O’Reilly’s show. How many Republicans does CNN take away from the Fox audience? My hunch: It will take a miracle for CNN to get better ratings than O’Reilly’s show, even with all these Republicans on the air. If CNN actually wins the hour, Republicans are more engaged in this race than anyone thought.