Republican presidential candidates campaign in Iowa - in pictures

A Mitt Romney supporter puts up signs before a campaign stop in Ames, Iowa Photograph: Evan Vucci/AP

Former House Speaker Newt Gingrich prepares for an interview on CNN's The Situation Room with Wolf Blitzer in Dubuque, Iowa Photograph: Dave Kettering/AP

US congresswoman Michele Bachmann dances with nine-year-old Shayne Holmes before a "meet and greet" campaign event in Marshalltown, Iowa Photograph: Win McNamee/Getty Images

A young supporter of Republican presidential hopeful Mitt Romney listens to his speech at a meeting with voters at the Music Man Square in Mason City, Iowa Photograph: Jewel Samad/AFP/Getty Images

Texas Governor Rick Perry leaves a campaign event at the Adams Street Espresso in Creston, Iowa Photograph: Jewel Samad/AFP/Getty Images

Rick Santorum waits to give a television interview after addressing supporters at the Button Factory Restaurant in Muscatine, Iowa Photograph: Rick Wilking/Reuters

Newt Gingrich and his wife, Callista, greet workers during a campaign stop at Southbridge Mall in Mason City, Iowa Photograph: Jim Young/Reuters

Members of Michele Bachmann's campaign team hold a sign for her to read during a campaign stop at the Nodawa, in Greenfield, Iowa Photograph: Evan Vucci/AP

A campaign sign for Ron Paul in front of a home in Des Moines, Iowa Photograph: Joshua Lott/Reuters

Texas Governor Rick Perry listens to a question during a campaign stop at the Westside Conservative Club breakfast, in Urbandale, Iowa Photograph: Eric Gay/AP

Supporters listen to former Massachusetts governor Mitt Romney at Homer's Deli and Bakery in Clinton, Iowa Photograph: Chris Carlson/AP

Ron Paul arrives for a town hall meeting at the Iowa Speedway in Newton, Iowa Photograph: Jewel Samad/AFP/Getty Images

A campaign staff member holds a chair as Mitt Romney speaks to a crowd at the Music Man Square in Mason City, Iowa Photograph: Jewel Samad/AFP/Getty Images

Former Utah governor Jon Huntsman speaks during a campaign stop at the Wright Museum, a second world war museum, in Wolfeboro, New Hampshire. Huntsman focused on New Hampshire, saying 'They pick corn in Iowa' Photograph: Charles Krupa/AP

Michele Bachmann, left, is toasted during a campaign stop at the home of Robin Read, right, in Shenandoah, Iowa Photograph: Eric Gay/AP