Gingrich pledges to release returns showing he pays 31 percent rate

Republican presidential candidate Newt Gingrich said Wednesday that he will release his 2010 tax returns on Thursday and estimated that he pays an income tax rate of about 31 percent, in contrast to front-runner Mitt Romney's admission that he pays only about 15 percent on his income.

"That's what I actually paid -- 31 percent of my income belonged to the government," Gingrich said when pressed by reporters on the second day of a burgeoning debate over the Republican candidates and their tax returns. "We do know, we've gone through this three times now to make sure we're, that, I paid at a 31 percent rate. We're pulling together the documents."

Gingrich said he didn't know if the 31-percent rate applied to both state and federal income taxes or only his federal income taxes, but he promised to release his 2010 returns on Thursday. After the controversy flared during Monday night's candidate debate, Romney said on Tuesday that he would release his 2011 tax returns in April, the federal filing date for taxes.

Asked how much money he earned annually before running for president, Gingrich said, "I don't know."

"We're going to release 2010 tomorrow, and then we'll match Romney and we'll release 2011 as soon as we put it together," he said.