"Speaker Gingrich is from a neighboring state, well-known, popular in the state, so I knew we'd have a long road ahead of us, and frankly to be in a neck-and-neck race at this last moment is kind of exciting," Romney told reporters.

Polls show Gingrich, who is from Georgia and is former speaker of the House of Representatives, gaining on Romney. The former Massachusetts governor's attempt to launch a knockout blow in the nomination race by winning the conservative southern state on Saturday is now in doubt.

Romney had another mixed debate performance Thursday night when he struggled to fend off queries about releasing his tax returns, after acknowledging this week that he pays a much lower tax rate than many working Americans. The former executive has an estimated worth of $270 million.