(CNN) -- Wednesday night's CNN debate lands at a critical moment in the Republican race. 

This season, each debate has set the tone for the primary to follow. Newt Gingrich's savaging of the media helped propel him to victory in South Carolina. Mitt Romney's savaging of Gingrich helped him to clinch Florida. The current uncertainty about the race, and the extraordinary elasticity in the polls, is partly due to the fact that we haven't had a debate for a whole month. 

It's important, then, for each of the candidates to make a powerful impression in this last confrontation before Arizona and Michigan vote on February 28. Rick Santorum and Newt Gingrich will compete over who is the most conservative, and Ron Paul will push his unique brand of libertarianism. Same old, same old. But we might see something new from Mitt Romney: a glimmer of humanity. 

The latest CNN/Time/ORC International Poll shows that Santorum is closing the gap on Romney in Arizona, but it's probably in Michigan that he stands the best chance of scoring an upset. A week ago, polls put Santorum as much as 10 points ahead in the Great Lakes State. But now they call it a statistical dead heat between him and Romney. 

So it would serve Santorum well to hit Mitt hard in the debate. This is Rick's natural style -- he gets a thrill out of counting the flaws of his opponents. But Santorum also probably recognizes that the only way he'll win Michigan is by reminding voters of the doubts that they have about Romney's conservatism. That's what he's been doing in the western part of the state all this week, where he has hit out repeatedly at Romney's "well-oiled weathervane" stance on issues like abortion and Iran. 
To what was his victory attributed?
savaging of the media