The twentieth Republican debate of the 2012 campaign once more showcased the topsy turvy nature of the fight for the GOP nomination, as Mitt Romney tangled with Rick Santorum, Newt Gingrich regained some lost footing and Ron Paul delighted his supporters in Mesa, Arizona.

Was there a clear winner? That probably depends on who you support.

But it might be easier to answer a different question - What happened to Rick Santorum?

Like Newt Gingrich in the two debates in Florida, Santorum just didn't seem to be able to get traction on a host of subjects that should have been easy fodder for good sound bites.

In fact, it was almost like Gingrich and Santorum changed bodies from the last debate in Jacksonville, Florida, where Gingrich was slow off the mark, while Santorum quietly scored some points against Romney.

This time it was Santorum who was a step slow, while Gingrich seemed relaxed and "cheerful" (to use his one word description of himself) in a way that boosted his debate performance.

It wasn't that Santorum had a "bad" debate - it just seemed like he didn't take advantage of some opportunities to score some points against Romney.

Instead of Santorum blasting out snappy attacks on the Obama White House over contraception requirements under the Obama health law, it was Romney who seemed to have the best lines.

Instead of Santorum jabbing repeatedly at Romney over earmarks and more, Santorum seemed to get caught in the weeds and wonky details about legislation on the Senate floor.

And as usual, Romney was ready with a few snappy one liners for Santorum.

"While I was fighting to save the Olympics, you were fighting to save the Bridge to Nowhere," Romney said to cheers.

Meanwhile, Santorum went into a lengthy explanation of "good earmarks and bad earmarks" which - when he finished - was received with deathly silence in the debate hall.

The debate crowd - which seemed very pro-Romney - booed Santorum several times, especially when Santorum discussed birth control.

As for Gingrich, the South Carolina version of Newt returned at times on Wednesday night, giving hope to his backers that he has one more surge left in him.

I said on the radio Wednesday that you should not count out Gingrich - and this debate was evidence of exactly that - as many of his backers loudly proclaimed on social media that Gingrich was the night's winner.

As for Ron Paul, he helped Romney tag team Santorum at various points during the debate, criticizing the record in Congress of the former Senator, and dismissing his explanations with lines like, "There's always an excuse."

When asked why he was running a television ad that called Santorum a "fake" conservative on the budget, Paul had a simple answer.

"Because he is a fake."

Will we look back on this debate like we look back on the Florida debates?

In other words, did Mitt Romney do enough in this GOP debate to lock up Arizona and Michigan?

Stay tuned.