Iowa caucuses

Creston, US: John Edwards and his wife head back to their campaign bus after greeting supporters and volunteers at an early morning house party Photograph: Steve Pope/EPA

West Des Moines, US: John Edwards speaks during the final stop of his 36-hour campaign tour around Iowa Photograph: Evan Vucci/AP

Atlantic, US: A bulletin board full of political memorabilia buttons, stickers and pins, adorns the kitchen at a house John Edwards visited Photograph: Steve Pope/EPA

Des Moines, US: Supporters of John Edwards wave signs at a huge rally Photograph: Steve Pope/EPA

Des Moines, US: Hillary Clinton meets campaign staff at her Polk county field office Photograph: Joe Raedle/Getty

Davenport, US: Hillary Clinton talks during a campaign stop at the Mississippi Valley fairgrounds Photograph: Joe Raedle/Getty

Indianola, US: Hillary Clinton talks to photographers on the media bus after delivering coffee and bagels Photograph: Stan Honda/AFP

Colo-Nesco, US: A sign supporting Hillary Clinton at a farm Photograph: Paul Sancya/AP

Coralville, US: Barack Obama works his way through a crowd of supporters Photograph: Mike Theiler/EPA

Davenport, US: Barack Obama speaks to voters from a makeshift podium during a rally Photograph: Scot Olson/Getty

Coralville, US: A woman puts a 'Babies for Obama' button on her child Photograph: M Spencer Green/AP

West Des Moines, US: Mitt Romney meets supporters at a campaign stop Photograph: Michal Czerwonka/EPA

West Des Moines, US: Mitt Romney attends a house party Photograph: Eric Thayer/Getty

Cedar Rapids, US: A supporter of Mitt Romney at a campaign stop at the Landmark Aviation hanger Photograph: Michal Czerwonka/EPA

Bettendorf, US: Mitt Romney gives a speech during a campaign stop Photograph: Michal Czerwonka/EPA

Davenport, US: John McCain speaks to supporters at Assumption high school Photograph: Larry W Smith/EPA

Dubuque, US: John McCain and his entourage board a private jet following a rally at the Dubuque Jet Centre Photograph: Scott Olson/Getty

Mason City, US: Fred Thompson during a campaign stop Photograph: Evan Vucci/AP

Perry, US: Mike Huckabee wearing cowboy boots as he speaks at a 'Meet Mike Huckabee' event Photograph: John Sullivan/Getty

Des Moines, US: Supporters greet Mike Huckabee during the Blogger Bash at the Marriott hotel Photograph: Justin Sullivan/Getty