Republican presidential candidate and former U.S. House Speaker Newt Gingrich speaks at the New Hampshire Institute of Politics at St. Anselm College in Manchester, N.H., Nov. 21, 2011. (ADAM HUNGER/REUTERS)

MANCHESTER, N.H.— Newt Gingrich fired back at Mitt Romney’s assertion that he can’t take the heat of a vigorous campaign, saying here Wednesday that he can “take the heat plenty well,” accusing his rival of hiding and challenging his rival to a one-on-one debate in Iowa next week to settle their differences.

Gingrich had earlier called on Romney to disavow the negative ads being aired in Iowa by a Super PAC that backs Romney’s candidacy. Romney in turn said that, if Gingrich can’t take the heat from those ads, he would hardly be prepared to deal with the “Hell’s Kitchen” that would come from President Obama’s campaign in a general election.

“You’re kidding, of course,” Gingrich said in Manchester when asked about Romney’s comments. “Look, I’ll tell you what. If he wants to test the heat, I’ll meet him anywhere in Iowa next week one on one, 90 minutes, no moderator,” he said.

Gingrich said he took considerable heat when he was House speaker and can stand up to whatever President Obama throws at him. He accused Romney of being afraid to stand up for the ads running in his behalf, which he said were false.

“Let’s test this kitchen,” he said. “I’m happy. I’ll go in the kitchen. Go back and ask Gov. Romney, would he like to play in the kitchen? I don’t think so. I don’t think he wants to do anything but hide over here and pretend it’s not his fault that he is flooding the people of Iowa with falsehoods. That’s his money and his staff and it’s his responsibility.”

Romney senior adviser Eric Fehrnstrom would not comment on whether the former Massachusetts governor would participate in a one-on-one debate, saying only, “We’ve debated him many times and we’ll debate him many more times I’m sure.”

Gingrich vowed again to remain positive but acknowledged that the weight of the ads in Iowa will have an effect on his candidacy. “I fully expect that in Iowa we will have to fight our way back,” he said, adding that his two-day trip to the state this week were “very positive.”

From New Hampshire, Gingrich flew back to Washington to concentrate his efforts on qualifying for the ballot in Virginia. He has been scrambling to get the required signatures but predicted he would meet the qualifications by the deadline.

Staff writer Philip Rucker contributed to this story.