Romney calls on Gingrich to release ethics violation report Mitt Romney has moved to fend off a late surge in support for Newt Gingrich in South Carolina's Republican primary election by calling on him to release a secret congressional report that saw Gingrich become the first speaker of the House of Representatives convicted of ethics violations. Romney's call comes as he attempts to deflect attention from his own refusal, repeated on Friday, to immediately make public tax returns on a fortune of more than $200m. A series of opinion polls put Saturday's race too close to call following a sharp rise in voter backing for Gingrich as social conservatives coalesced around him in an attempt to block Romney, who is suspect for his previous support of abortion rights, gay marriage and government intervention in health care, from winning the nomination. All the candidates made a last ditch effort to win over the large number of undecided voters with swings across the largely religious and conservative state and a blitz of television advertising and phone calls. In a fresh wave of adverts, Romney pressed home his claim that he is best positioned to beat President Barack Obama - an assertion backed by nationwide opinion polls. But he has been on the defensive over his tax returns with Gingrich implying during Thursday's televised debate that Romney may have something to hide. Gingrich said he saw no reason why Romney should not release last year's returns if there was nothing in them to embarrass him, and if there is then he should let the Republican party know before he becomes the nominee and Obama can use them against him. Gingrich added to the pressure by releasing his own returns which show that he earned $3.1m in 2010 and paid tax of 31.5%. On Friday, Romney sought to throw that back at Gingrich by suggesting that a report from a 1997 Congressional ethics investigation into the then-speaker of the House of Representatives' conduct, which resulted in him being fined $300,000, is a time bomb that the Democrats will release when it suits them. Romney called on Gingrich to make the report public now. "[Former Democratic speaker of the House] Pelosi has a full record of that ethics investigation ... it's going to get out," he said during a campaign stop in Gilbert. Romney's backers had spent the morning in conference calls attacking Gingrich's congressional record. In Gilbert, South Carolina governor Nikki Haley, who has endorsed Romney and was at his side, told reporters who had asked about his tax returns: "The people of South Carolina are not talking about tax returns. They're not. They're talking about jobs, spending and the economy. In all honesty, I've heard more people wondering why you guys aren't asking about ethics reports and ethics problems with the Gingrich campaign. Gingrich was fined over the financing for two projects he supported and for giving the ethics committee false information, but the full report on the affair has never been made public. Romney's attempts to put Gingrich's ethics on trial follow the dramatic showdown at Thursday's debate over the opening question about allegations by one of Gingrich's former wives, Marianne, that he asked for an open marriage so he could continue an affair with the woman who is now his wife, Callista. Gingrich's theatrical and blistering attack on the media over the question will have endeared him to many Republicans looking for someone to take the battle to Obama. But opinion among pundits was divided on what impact the allegations will have on the large numbers of deeply Christian voters in South Carolina as they remind evangelicals of past infidelities that have already caused some to say Gingrich is an unfit candidate. Polling suggests women voters are particularly wary of Gingrich. The latest opinion polls offer an array of outcomes from a Politico poll that put Romney seven points ahead to a Public Policy Polling survey that gave Gingrich a six-point lead. Other polls put the race much closer. The other candidates, Rick Santorum and Ron Paul, were far back in the field. A win for Romney in South Carolina would see him remain favourite to take the Republican nomination. But a loss to Gingrich would probably result in a protracted and bloody political battle, as the fight moves on to Florida, that would delay the Republican campaign to unseat Barack Obama. One key Romney supporter, former New Hampshire governor John Sununu, predicted the nomination race will be a long one. Asked what Romney will do if he loses South Carolina, Sununu said: "He has never suggested one or two or three primaries and caucuses would make a difference. It has been designed for a long slog. He compared the race to the Ford-Reagan one in 1976, which went all the way to the party convention in the summer. Sununu dismissed the tax issue, asking journalists what they expected to find in his tax returns. "Are you going to be surprised when it turns out he is rich?" he said. Sununu said the surprise will be how generous Romney is in giving to charity. National polls continue to show that Romney maintains a clear lead among Republican voters. A Pew Forum poll released on Thursday gave Romney 31% support, nearly double that received by Gingrich. Republican voters overwhelmingly said they believe Romney has the best chance of beating Obama. Among the undecided South Carolina voters is Kristen Stoudenmire, a hairdresser in the conservative northwest of the state who said her principal concern is the economy because she and her husband do not earn enough to afford health insurance and they are about to have a baby and face thousands of dollars in doctors bills. It's jobs and the economy. I'm leaning to Romney. I'm looking at who can improve the economy. We need the better jobs. I think Romney is better on that," she said. We're struggling, really struggling. We have to come up with $4,000 for the doctor and that's even before the delivery. Dave Crook, a salesman, thought differently. Romney is like Bush. Nothing will change. He'll be for big government. We need someone radical. I favoured Perry but it's Newt who can win and so that's who I'll vote for," he said. South Carolina holds an open primary which means any resident of the state can vote whether they support the Republican party or not. But while African Americans make up more than a quarter of South Carolinians, only a tiny proportion are expected to vote in an election tinged with racism, including Gingrich's implication that black people are reluctant to work and are the principal beneficiaries of government food stamps. However, the open primary has also opened the way for popular satirist Stephen Colbert, to call for voters to back his bid to be "president of the United States of South Carolina" by voting for Herman Cain, who dropped out of the race but whose name is still on the ballot. Colbert led a rally in Charleston where Cain took to singing and Colbert attacked Romney's much derided flip flops on abortion, gay marriage and health care. "The only difference between Mitt Romney and a statue of Mitt Romney is that a statue never changes its position," he said.