Iowa caucuses

Mitt Romney -- with his wife, Ann, and some of their sons -- speaks to supporters in Des Moines.  (Win McNamee / Getty Images)

Supporters of Republican presidential hopeful and former U.S. Sen. Rick Santorum wait for their candidate to arrive at the Stoney Creek Inn in Johnston, where he will find out the final results of the Iowa caucuses.  (Andrew Burton / Getty Images)

Republican presidential candidate, Texas Rep. Ron Paul and his wife, Carol, greet supporters at a rally at the Courtyard Des Moines Ankeny in Ankeny, Iowa.  (Justin Sullivan / Getty Images)

Texas Gov. Rick Perry waits to speak to caucus-goers at a precinct in West Des Moines.  (Jonathan Gibby / Getty Images)

Voters register at the Republican caucus in Ankeny, Iowa.  (Justin Sullivan / Getty Images)

Karen Santorum looks at her husband, Republican presidential hopeful Rick Santorum, during a campaign event in West Des Moines.  (Justin Sullivan / Getty Images)

Former Massachusetts Gov. Mitt Romney campaigns in Des Moines.  (Chip Somodevilla / Getty Images)

Republican presidential candidate Newt Gingrich makes a campaign stop in Muscatine, Iowa.  (T.J Kirkpatrick / Getty Images)

Lynn Kozak, a supporter of Texas Gov. Rick Perry, makes her view known at the site of the Waukee Precinct 4 caucus in Urbandale, Iowa.  (Jonathan Gibby / Getty Images)

Former Utah Gov. Jon Huntsman Jr. speaks to workers at Tidland Corp. in Keene, N.H. The state holds its primary on Jan. 10.  (Matthew Cavanaugh / Getty Images)

Former House Speaker Newt Gingrich makes a campaign stop at Elly’s Tea in Muscatine, Iowa.  (T.J. Kirkpatrick / Getty Images)

Rep. Michele Bachmann (R-Minn.) speaks at a Rock the Caucus event at Valley High School in West Des Moines.  (Justin Sullivan / Getty Images)

Rep. Ron Paul (R-Texas) watches a Rock the Caucus event at Valley High School in West Des Moines, as candidates made a final push ahead of caucuses.   (Justin Sullivan / Getty Images)