The main event in today's GOP debate will of course be the interplay between Mike Huckabee and Mitt Romney. But also keep your eye on the lesser candidates hustling for third place in Iowa. Yesterday I argued that Ron Paul has a shot at coming in third, and that Fred Thompson in particular will be ruined if he does. But Rudy Giuliani and John McCain would both dearly love to score a third-place finish. That would enable them to argue that they had surpassed exceeded in a state they never wasted much effort on. So watch to see if Rudy, McCain, and Fred form a firing squad--and also whether anyone is spooked enough by the Ron Paul scenario to take him on directly.

Also: John McCain will almost surely be asked about his opposition to ethanol and farm subsidies. Telling an Iowa audience that ag subsidies should end is like calling for the abolition of Social Security at an AARP convention. Should be fun to watch how he handles it.

Update: My colleague Chris Orr argues that it's Rudy who should truly fear Ron Paul--not Fred, who is "doomed regardless."

--Michael Crowley