The Republican presidential race is tightening in South Carolina, where Mitt Romney’s lead over Newt Gingrich is shrinking in the final days before Saturday’s primary, according to a new CNN/Time/ORC International poll. Romney continues to maintain a strong lead in Florida, which holds the next primary on Jan. 31. The South Carolina poll found that 33 percent of respondents are backing Romney, the former Massachusetts governor, compared to 23 percent for Gingrich, the former House speaker. That’s a shift in Gingrich’s favor from a Jan. 4-5 poll when Romney was ahead of Gingrich, 37 percent to 18 percent.