Gingrich comeback narrows Romney lead Mitt Romney's lead in national polls has narrowed after a comeback by Newt Gingrich, according to two surveys that could energise his rivals who are scrambling to prevent him from quickly clinching the Republican presidential nomination. A survey by Rasmussen released on Wednesday showed Mr Romney still in first place among Republican voters, with 30 per cent of preferences. But Mr Gingrich, the former speaker of the House of Representatives, was trailing just three percentage points behind, at 27 per cent. A CBS/New York Times poll showed Mr Romney, the former Massachusetts governor, with a seven percentage point advantage over Mr Gingrich. In the wake of Mr Romney's resounding victory in the New Hampshire primary last week, polls had shown him opening up ample double digit leads over his closest rivals, raising the possibility that the fight for the Republican nomination could be sealed in his favour by the end of the month. But Mr Romney fared poorly - and Mr Gingrich performed strongly - at a debate on Monday night in South Carolina that might have convinced some undecided voters to turn away from the frontrunner. The latest polls in South Carolina showed Mr Romney still comfortably ahead in the southern state - which holds its primary on Saturday - with a 10 percentage point lead over Mr Gingrich, according to an average calculated by Realclearpolitics. Mr Romney has been battered by his rivals on his record as a private equity executive at Bain Capital, and most recently on his hesitancy to release his tax records. Under pressure, Mr Romney on Tuesday suggested he might disclose his tax information in April, and revealed that he has paid a tax rate of about 15 per cent in recent years. But far from quashing the criticism, this further inflamed the debate over Mr Romney's wealth, since he is paying taxes at roughly the same rate as many middle-class Americans despite his high earnings due to the preferential treatment of investment income, where Mr Romney generates most of his money. Mr Romney may have compounded his problems when he said he was bringing in "not very much" money from speaking engagements that earned him $374,327. "Thirty-one per cent of my income belonged to the government," Mr Gingrich said at a campaign stop in South Carolina on Wednesday. Touting his plan for a 15 per cent optional flat tax, he added: "My goal is not to raise Mitt Romney's taxes; it's to let everybody pay Mitt Romney's rate." Sensing the mounting threat from Mr Gingrich, Mr Romney's campaign released a new web advertisement criticising the former House speaker as an "unreliable leader." "He would make outrageous comments that would blindside us and undermine our conservative agenda," Jim Talent, a former Republican congressman who served with Mr Gingrich, said in the ad, in which he also cited the former speaker's "chaotic decisions" and "erratic behaviour." In addition, at a campaign stop on Wednesday, Mr Romney said any claims of job creation coming from Mr Gingrich - and possibly even Rick Santorum, a former Pennsylvania senator who is running third in the South Carolina race, were bogus. "Congressmen taking credit for helping create jobs is like Al Gore taking credit for the internet," Mr Romney said.