Former House Speaker Newt Gingrich rebuffed calls for him to drop out of the Republican presidential race on Monday, saying he could still prevail in a tumultuous and unpredictable race.

The National Review, a flagship conservative publication, had renewed its call for Gingrich to end his candidacy and endorse Rick Santorum's resurgent campaign. Gingrich brushed off the National Review editorial and said his policy ideas set him apart from Santorum and Mitt Romney.

I think my ideas are much bolder than Santorum or Romney's, Gingrich told reporters in California. I think my ideas are much clearer and more specific and I have to focus on communicating those ideas. Let's see how it plays out.

Gingrich: I'm Still Here

Gingrich has struck a similarly defiant note since positioning himself as the conservative alternative to Romney, a designation he is loathe to concede to Santorum. The former House Speaker had vowed to fight until the Republican National Convention shortly before a crushing loss in the Florida primary, and on Monday he brushed aside the wins in Minnesota, Missouri and Colorado that catapulted Santorum back into contention.

He [Santorum] had a really good Tuesday and suddenly the same people who said I was dead in June are saying, 'See, I told you so,' Gingrich said. I have a message for them - I'm still here.

Gingrich's campaign strategy is focused on southern states like Georgia and Tennessee, where Gingrich hopes to fare well with conservative voters like those who handed him a win in South Carolina.

Our commitment is to find a series of victories which, by the end of the Texas primary, will leave us at parity with Governor Romney. And by that point forward, we'll see if we can't actually win the nomination, Gingrich told reporters after Romney trounced him in Nevada.