Wisconsin Governor Scott Walker is holding a news conference at 5pm in Madison, where he is expected to announce he is suspending his campaign for President.
Both CNN and Fox News reporting Walker has decided to drop out.
Walker was at one time the frontrunner in Iowa, but has seen his position in the polls fall sharply since the first debate.
Governor Rick Perry of Texas is the only other Republican to drop out so far.
Donald Trump, Carly Fiorina, and Dr. Ben Carson, all political outsiders, are leading in various recent Republican polls.