OKLAHOMA CITY (AP) Rick Santorum has won Oklahoma's Republican presidential primary, leaving Mitt Romney and Newt Gingrich to battle for second place in what is called the "reddest of the red" states.

With half the state's 1,961 precincts reporting unofficial returns, the former Pennsylvania senator had 35 percent of the vote. Former House Speaker Newt Gingrich had 27.4 percent and former Massachusetts governor Mitt Romney had 26.8 percent.

Santorum made Oklahoma a priority and visited the state twice in recent weeks, calling it "ground zero of the conservative movement." Four years ago, Barack Obama failed to win a single of the state's 77 counties.

Santorum said Oklahoma fit him well and that he appealed to the conservative base of the Oklahoma Republican Party. Exit polling showed 75 percent of voters considered themselves evangelicals.

Delaware and Ottawa County figures show Santorum with the majority, however, all precincts are not in yet.