Texas Gov. Rick Perry speaks at a campaign event at Clark Electric Co-op on Dec. 27 in Osceola, Iowa. Perry's stance on immigration has troubled some Iowa voters. Justin Sullivan/Getty Images hide caption

itoggle caption Justin Sullivan/Getty Images

In a last bout of campaigning before Christmas, Rep. Michele Bachmann of Minnesota signs autographs at the National Motorcycle Museum in Anamosa, Iowa, on Dec. 22. Charlie Riedel/AP hide caption

itoggle caption Charlie Riedel/AP

Republican presidential candidate former House Speaker Newt Gingrich speaks during a Republican presidential debate in Sioux City, Iowa, Thursday, Dec. 15, 2011. Eric Gay/AP hide caption

itoggle caption Eric Gay/AP

Republican presidential candidates jockeyed for airtime when they met for their first prime time TV debate on Saturday night in South Carolina. Alex Wong/Getty Images hide caption

itoggle caption Alex Wong/Getty Images

Herman Cain (right) speaks as Texas Gov. Rick Perry looks on during a GOP presidential debate at Dartmouth College on Oct. 11.

Andrew Harrer/AFP/Getty Images hide caption

itoggle caption Andrew Harrer/AFP/Getty Images