Former winners of the Iowa caucus (18 images)

Incumbent President Barack Obama won the 2012 Iowa Republican caucus as he ran unopposed. He went on to be re-elected after he won the presidential election over Republican candidate Mitt Romney. Pictured: Obama speaks at an interfaith vigil for families of the victims as well as families from Sandy Hook Elementary School on December 16, 2012 at Newtown High School, Newtown, Connecticut. Pool photo by Olivier Douliery/UPI

Republican presidential candidate and former Pennsylvania Sen. Rick Santorum was officially declared the winner of the 2012 Iowa caucuses after he initially tied with eventual nominee Mitt Romney. Santorum suspended his campaign after the hospitalization of his daughter Bella and losses in Maryland, Wisconsin, and the District of Columbia. Pictured: Santorum (C) jokes acquaintance Jim Giboons (L) as he arrives with his wife Karen (L) to meet supporters at the Pizza Ranch, campaigning in Boone, Iowa, January 2, 2012 in advance of Iowa's first-in-the-nation caucuses, January 3. Photo by Mike Theiler/UPI

U.S. President Barack Obama was the winner of the 2008 Iowa Democratic Caucus with 37.6 percent of the votes, which made him the first African-American candidate to ever win it. Then-Senator John Edwards of North Carolina came in second place and Former Senator Hillary Rodham Clinton came in third. Pictured: Obama makes a campaign stop at Roosevelt High School while campaigning for the Iowa Caucus in Des Moines, Iowa on January 1, 2008. Photo by Laura Cavanaugh/UPI

Mike Huckabee finished first in the 2008 Iowa Republican caucus with 34 percent of the vote. Huckabee later finished second in delegate count and third in the overall popular vote and number of states won. He exited the race as McCain became the presumptive Republican nominee after winning in Florida, California and New York. Pictured: Huckabee attends a rally at the Veterans Memorial Building during the final day of campaigning before the Iowa Caucus in Grinnell, Iowa on January 3, 2008. Photo by Laura Cavanaugh/UPI