U.S. Republican presidential candidate, former Pennsylvania Senator Rick Santorum attends a caucus night event in Johnston near Des Moines, capital of Iowa, the United States, Jan. 3, 2012.

Former Pennsylvania senator Rick Santorum and former Massachusetts governor Mitt Romney were tied in Iowa Caucuses on Tuesday night, with only a razor-thin margin separating the two after more than 99 percent of the votes are counted.

The two front-runners were tied at about 25 percent, with Santorum edging Romney by only 4 votes. The two are heading to next contest a week later at New Hampshire to fight it out.

Ron Paul, the libertarian-leaning congressman from Texas, came in third with 21 percent of the vote, followed by Newt Gingrich, the former House speaker and Rick Perry, the Texas governor. Perry has announced he's returning to his home state to "reassess" his campaign.

Michele Bachmann, the Minnesota congresswoman, was in a disappointing sixth place. Jon Huntsman, the former ambassador to China, came in seventh.