CHICAGO (Reuters) - Mitt Romney won the Illinois Republican presidential primary on Tuesday, Fox news projected, giving the front-runner momentum in the volatile campaign for the White House.

With just 3 percent of the vote counted, Romney was leading with 54 percent while his closest rival Rick Santorum had 28 percent, Fox said. Ron Paul was in third followed by Newt Gingrich.

None of the other networks have yet called the race, saying it was still too early.

(Reporting by Lily Kuo and Deborah Charles; Editing by Eric Beech)