Republican White House hopeful Mitt Romney convincingly won the Nevada caucus Saturday, US media projected, solidifying his position as frontrunner in the race to be the party's 2012 presidential nomination.

With nearly all polls in the western US state closed and about 10 percent of caucuses reporting, Romney had a decisive lead with 48 percent of the vote, CNN reported, leaving his main rival Newt Gingrich in a tight battle for second place with Texas Representative Ron Paul.