Tonight's debate was an interesting one. Gingrich has apparently tried to go back to Newt 2.0 mode, by turning down the vitriol and righteous indignation. It's unclear how convinced voters will be by this change, however, since it comes after Newt 1.0's explosive reappearance in South Carolina.
Romney's attacks seemed to unsettle Gingrich. At one point, the former Speaker had to pause for a few moments to collect his thoughts to respond. The famously loquacious politician was at an apparent loss for words. Romney hit Gingrich hard on his connections to Freddie Mac and his record as Speaker. Though Gingrich tried, he seemed unable to beat off Romney's criticisms fully. Meanwhile, Romney kept turning the course of the debate to the failures of the Obama administration and emphasizing Romney's own conservative bona fides (for example, his strong stand on immigration enforcement).
Santorum stressed that his own record was one of consistent conservatism. He didn't pile on Gingrich, but he didn't refrain from criticizing him either.
It's clear that Gingrich got no winning soundbite moments out of this debate. His campaign in South Carolina depended upon those. The lack of fire in this debate may slow Gingrich's momentum. For the past week, the narrative of his campaign has been one of explosive growth; it's hard to see how tonight will add to that growth rate. Any slowing in his support could be a signal that momentum has begun to be reversed. And Romney was able to land some effective blows tonight, muddying Gingrich's claim that he is the true conservative. Gingrich walked into this debate with great expectations, and he didn't actually deliver. This was an attempt to sell himself as a candidate who can still win in a restrained debate. We'll have to see whether the public buys this image.