"I have nothing in them that suggests there's any problem and I'm happy to do so," he said. "I sort of feel like we're showing a lot of exposure at this point," he added in an apparent reference to the campaign to come against Democratic President Barack Obama.
Romney came under criticism from the opening moments of the debate, the first of two in the run-up to this weekend's first-in-the-South primary in South Carolina. The former Massachusetts governor won the first two events of the campaign, the Iowa caucuses and last week's New Hampshire primary, and leads in the pre-primary polls in South Carolina.
One of his rivals, Newt Gingrich, has virtually conceded that a victory for Romney in South Carolina would assure his nomination as Obama's Republican rival in the fall, and none of the other remaining contenders has challenged that conclusion.
That only elevated the stakes for the debate, feisty from the outset as Gingrich, Texas Gov. Rick Perry and former Pennsylvania Sen. Rick Santorum sought to knock Romney off stride.