TAMPA, Fla. (AP) -- Unwilling to wait for an evening debate, Republican presidential rivals Mitt Romney and Newt Gingrich got a head start on the squabbling on Monday in a campaign turning more caustic by the day.
Romney, trounced by Gingrich in last weekend's weekend South Carolina primary, began airing a harshly critical new campaign ad and said the former House speaker had engaged in "potentially wrongful activity" with the consulting work he did after leaving Congress in the late 1990s.
Gingrich retorted that Romney was a candidate who was campaigning on openness yet "has released none of his business records."
He followed up two hours before the debate by arranging the release of a contract his former consulting firm had with the Federal Home Loan Mortgage Corp. for a retainer of $25,000 per month in 2006, or a total for the year of $300,000. The agreement called for "consulting and related services."
Despite Romney's attempts to call Gingrich a lobbyist, the contract makes no mention of lobbying.
Aside from Romney and Gingrich, former Pennsylvania Sen. Rick Santorum and Texas Rep. Ron Paul had spots on the debate stage for the first of two encounters scheduled before the Jan. 31 Florida primary.
Increasingly, though, the race for the nomination appeared to be a two-way competition between the former Massachusetts governor and the one-time speaker of the House.
After relying on allies to make most of the attacks on his rivals earlier in the campaign, Romney unleashed a commercial that went straight at Gingrich.
"While Florida families lost everything in the housing crisis, Newt Gingrich cashed in," the TV ad says, noting that the former speaker made more than $1.6 million working for Freddie Mac. "Gingrich resigned from Congress in disgrace and then cashed in as a D.C. insider."
Gingrich never registered as a lobbyist, but said he was a consultant for Freddie Mac, the federally backed mortgage company that played a significant role in the housing crisis.
It remains to be seen if Romney can effectively use his newly aggressive stance on the debate stage, a forum in which Gingrich has excelled so far. Underfunded and overmatched by Romney's massive ground game across the country, Gingrich has relied upon strong debate performances to build support.
It appears Romney has brought in outside help to improve his debate technique.
Veteran debate coach Brett O'Donnell was spotted at a Romney campaign stop on Monday. He previously advised President George W. Bush and GOP nominee John McCain and was a senior adviser and speech writer for Michele Bachmann's abbreviated campaign.
Gingrich showed no signs of backing down.
During an appearance on ABC's "Good Morning America," he referred to Romney as "somebody who has released none of his business records, who has decided to make a stand on transparency without being transparent." After initially balking, Romney is set to release personal tax records on Tuesday.