U.S. presidential hopeful Newt Gingrich has surged in opinion polls ahead of voting in the South Carolina primary, the latest leg of the battle to be the Republican challenger to Barack Obama in 2012.
Despite scandal surrounding an ex-wife's claim that he wanted an open marriage, Gingrich was 6 percent ahead of Mitt Romney in one opinion poll on the eve of the crucial vote.
Romney, a former Massachusetts Governor, said the race was "neck and neck".
The South Carolina vote on January 21 is seen as a crucial test for the four remaining contenders, which also include Texas Congressman Ron Paul and former Pennsylvania Senator Rick Santorum.
compiled from agency reports