The war of words between GOP presidential hopefuls Mitt Romney and Newt Gingrich heated up Monday when both candidates called for the other to return monies they had earned in less-than-honorable ways.

In an interview on Fox & Friends, host Brian Kilmeade asked Romney if Gingrich should give back the $1.6 million he was paid by the government-sponsored Federal Home Loan Mortgage Corporation, otherwise known as Freddie Mac.

"Boy, I sure do," Romney replied. "He was in the business of connecting folks with government. He was on K Street. ... One of the things that people recognize in Washington, is that people go there to serve the people, and then they stay there to serve themselves."

For his part, the former House Speaker has denied that he ever acted as a spokesman or a lobbyist for Freddie Mac, which he claims was part of the “private sector.”

Speaking to reporters after a campaign event in Londonderry, New Hampshire Monday, Gingrich had a strong reaction to Romney's comments.

"If Governor Romney would like to give back all the money he's earned bankrupting companies and laying off employees over his years at Bain, then I would be happy to at least listen to him," the Georgia Republican remarked. "I would bet you $10, not $10,000, that he won't take the offer."

As the head of Bain Capital, Romney helped negotiate deals to buy about 150 companies, which later resulted in thousands of layoffs. Because the the data has not been made public, it's difficult to tell exactly how many jobs were lost.

In one example, Bain cut over 1,600 jobs after buying medical-testing company Dade Behring Inc. in 2002.

"Sometimes the medicine is a little bitter," Romney told The New York Times in 2007. "But it is necessary to save the life of the patient."

Watch this video from Fox News' Fox & Friends, broadcast Dec. 12, 2011.

Watch this video from CNN, broadcast Dec. 12, 2011.