Aides to the former governor refused to expand on the information, declining to say how large his investment is in the Cayman Islands and why it is there, as opposed to in the U.S.

A spokeswoman for Romney's campaign confirmed that the Romneys have money in the Caymans. But the campaign did not say why. Spokeswoman Andrea Saul also said: "ABC is flat wrong. The Romneys' investments in funds established in the Cayman Islands are taxed in the very same way they would be if those funds were established in the United States. These are not tax havens and it is false to say so."

Romney's campaign was confronted with new questions about his finances Wednesday when ABC News reported that Romney has millions of dollars of personal wealth in investment funds set up in the Cayman Islands, known as a tax haven for Americans. The report said that Romney had the ability to pay a lower tax rate by investing in funds located offshore.

Texas Gov. Rick Perry says he intends to push it anew on Thursday. "If Mitt Romney intends to be our nominee, he needs to open up his tax records today, no later than tomorrow by debate time," Perry told CNN on Wednesday.

"My goal is not to raise Mitt Romney's taxes but to let everyone pay Romney's rate," Gingrich said.

Gingrich told reporters that he is not criticizing Romney for paying a tax rate below what many wage-earning Americans pay. Gingrich has proposed a plan that would give Americans the option of paying a 15 percent flat tax -- which he notes is the same rate Romney is citing.

Gingrich slapped at the GOP front-runner, saying in Winnsboro that he himself paid 31 percent of his income in taxes for 2010, more than twice what Romney said he paid. Gingrich's campaign said the 31 percent was the effective federal rate on income, apparently not including Social Security payroll taxes.

Just before Saturday's South Carolina voting, Romney is trying to wrap up his push for the Republican nomination, but it's been anything but smooth. He's spent nearly two weeks answering questions and criticism about his personal wealth and tenure at Bain Capital, the private equity firm he founded, and those subjects are sure to come up again in Thursday night's debate.

Newt Gingrich, his main rival in this weekend's South Carolina primary, poked at Romney anew and disclosed that his personal tax rate is more than double that of Romney.

Facing a new controversy, his campaign confirmed that Romney has money invested in the Cayman Islands but said he was not getting any tax break.

SPARTANBURG, S.C.—Mitt Romney tried doggedly Wednesday to sidestep the political furor he had started a day earlier by revealing he pays federal taxes at a rate of about 15 percent, less than millions of middle-income American families.

Nor would the campaign say whether Romney has investments anywhere else outside the United States. Advisers said Romney's assets are managed on a blind basis and that he does not have control over how they are managed.

Romney also refused to answer repeated questions from reporters about his Cayman investments during a stop at a barbecue restaurant in Lexington. Outside Hudson's Smokehouse, Romney simply smiled for cameras as he pushed through the crowd and boarded his campaign bus.

While a supporter rushed to Romney's defense, the former Massachusetts governor tried to duck the issue entirely on Wednesday, making no mention of his tax returns or tax rate during a rally at Wofford College here and declining to take questions from the news media. Instead, he delivered his standard campaign speech and assailed Gingrich, who has been running second in opinion polls in South Carolina.

Romney aides, too, refused to comment about his tax returns or details of his tax rate when pressed. His campaign held a conference call featuring surrogates who tried to cast Gingrich, the former House speaker, as an unreliable leader, but the wealth and taxes issue showed no signs of going away.

At an event in Rock Hill, S.C., Romney kept away from the issue of his taxes, but he criticized Republicans who "jumped on that bandwagon" of criticizing free enterprise. "My goodness, I listened to Speaker Gingrich the other night talk about the enterprises I've been associated with," Romney said. "I'm proud of the fact that I worked in the private sector, that I've achieved success."

New Jersey Gov. Chris Christie, who has endorsed Romney, sought to help by defending Romney's tax status on TV. But that may have backfired when Christie, on NBC's "Today" show, suggested Romney put out his tax returns "sooner rather than later."

"It's always better in my view to have complete disclosure, especially when you're the front-runner," Christie said.

After months of resistance and under pressure from Republican presidential rivals, Romney now says he will release tax information for 2011 -- but not until April, close to the tax filing deadline and when, presumably, the GOP race will have been decided.

Romney disclosed for the first time on Tuesday that, despite his wealth of hundreds of millions of dollars, he has been paying in the neighborhood of 15 percent, far below the top maximum income tax rate of 35 percent, because his income "comes overwhelmingly from investments made in the past." During 2010 and the first nine months of 2011, the Romney family had at least $9.6 million in income, according to a financial disclosure form submitted in August.