WASHINGTON - US Republican candidates Mitt Romney and Newt Gingrich, the two perceived front-runners in the forthcoming Republican primary in Florida, on Monday faced off in a campaign debate in Tampa, Florida, drawing the spotlight as the remaining four candidates in the party engaged in their 17th primary debate so far.

Romney and Gingrich engaged in exchanges from the start of the debate as they accused each other of being unfit for the Republican nomination.

Gingrich, who came back from the cold with a surprising win in South Carolina over the weekend, was faced with an unusually combative Romney, who attacked his tenure as House speaker and work with Freddie Mac afterwards.

Romney accused Gingrich of influence peddling, and the exchange became so heated that the moderator has to step in and announce a commercial break. He demanded Gingrich release the content he provided with Freddie Mac as a consultant.

Shortly before the debate, Gingrich's former consulting firm released a contract with Freddie Mac in 2006, shedding little light on what Gingrich was hired to do. The document showed the firm earned a 300,000-dollar retainer and 25,000 dollars in monthly fee for a year. Gingrich adamantly denied he worked as a lobbyist.

Apart from Romney and Gingrich, former Pennsylvania senator Rick Santorum and Texas Congressman Ron Paul both participated in the debate, but with one week to go to the Florida primary, the debate holds higher stake to Romney and Gingrich.

Gingrich has used muscular performances in two debates before South Carolina primary to salvage his campaign and pull off a 12 point lead over Romney. It showed how much debate performances hold swing over undecided voters.

According to US media report, Romney, who was outshone by Gingrich in South Carolina debates, has hired a top debate coach to help him perform better. His campaign holds the upper hand in Florida with better organization and more ad buys.