Former Republican presidential candidate Newt Gingrich on Sunday admitted that GOP hopeful Mitt Romney had "changed" positions during last week's debate when he claimed that he had not proposed a $5 trillion tax cut.

“I don’t have a $5 trillion tax cut,” Romney had insisted on Wednesday. “I don’t have a tax cut of a scale that you’re talking about.”

But an analysis by the the non-partisan Tax Policy Center had concluded earlier that Romney’s plan would reduce revenue by $480 billion in 2015 and $5 trillion over 10 years.

"Speaker Gingrich was pretty eloquent in running during the primaries, saying, 'Look, Mitt Romney will say absolutely anything to get elected,'" Obama senior campaign adviser Robert Gibbs recalled during an NBC panel discussion on Sunday. "There's a $4.8 trillion reduction in revenue, OK? According to Mitt Romney's own plan, there's a 20 percent rate reduction from the Bush tax cuts. We're going to end the estate tax. We're going to cut the corporate tax rate from 35 to 25 percent. You cannot sit here, Mr. Speaker, and say that doesn't require a reduction in the amount of revenue by $4.8 trillion. This is math."