This was not one of Romney's stronger debate performances. He stumbled when confronted by Rick Santorum about super PAC ads. His answer on whether he'd release his personal tax returns was a muddled mess.

But, it wasn't bad enough to derail his momentum as the frontrunner going into Saturday's Republican primary in South Carolina.

As has been the case for the entire primary process, none of Romney's opponents was able to make a clear, consistent or substantive case for why Romney shouldn't be the nominee - or, more important, why one of them SHOULD be the party's standard bearer this fall.

Instead, it felt like four candidates going through the motions of yet another debate (their 16th), while one - Romney - tried to run out the clock.

Gingrich had a solid debate performance, perhaps his strongest since the ABC/Des Moines Register debate in early December. Yet, his most memorable exchange was with Fox News moderator Juan Williams, not Romney.

Santorum tried to engage with Romney early on but, as he has done in previous debates, he spent more of his time arguing with Ron Paul over foreign policy.

Perry, who is in a distant fifth place in South Carolina, took some swings at Romney early on, but by the middle of the debate his focus wavered to attacking Washington and the Obama administration.

In the end, Newt's performance could help give him some needed momentum over Rick Santorum is nipping at his heels.

Still, this debate did not have the feel of a "game changing" event. If one of these candidates really, truly, wanted to distinguish himself from Romney, this was the night to do it. No one did. That means the ultimate winner tonight, by default, was Mitt Romney.