WASHINGTON (Reuters) - Former Massachusetts Governor Mitt Romney scored a narrow victory over Rick Santorum to win the Republican presidential primary in Ohio, television networks projected.

Romney, who had trailed Santorum in the state for most of the night, was 12,000 votes ahead with 96 percent of the vote counted. He was declared winner in five races so far on Super Tuesday.

(Reporting by Deborah Charles; Editing by Vicki Allen)