Super Tuesday campaign trail

Washington DC, January 28: Barack Obama and Edward Kennedy at a campaign rally Photograph: Chip Somodevilla/Getty

Los Angeles, California, January 31: California Governor Arnold Schwarzenegger endorses Senator John McCain, right, as former New York Mayor Rudy Giuliani looks on Photograph: Charles Dharapak/AP

San Diego, California, January 31: A republican supporter wears a helmet with a badge that reads, "Wake Up America No Illegals", at a rally for Mitt Romney Photograph: Joe Raedle/Getty

Los Angeles, California, January 31: Democratic candidates, Barack Obama and Hillary Clinton are seen on monitors during a televised debate at the Kodak Theatre Photograph: Gabriel Bouys /AFP

San Diego, California February 1: Hillary Clinton greets supporters at a rally Photograph: Justin Sullivan/Getty

Birmingham, Alabama, February 2: John McCain speaks on his phone before boarding his campaign plane Photograph: Mario Tama/Getty

New York, February 2: Republican presidential hopeful Ron Paul takes questions during the MTV/ MySpace "Closing Arguments" forum Photograph: Scott Gries/Getty

Minneapolis, Minnesota, February 3: Republican candidate and former Massachusetts governor Mitt Romney prepares for live television interviews Photograph: Joe Raedle/Getty

Los Angeles, California, February 3: A supporter sheds a tear as Michelle Obama, wife of Barack Obama, speaks at a campaign rally Photograph: David McNew /Getty

Los Angeles, California, February 3: Stevie Wonder sings his support at a Get Out the Vote rally supporting Barack Obama Photograph: Phil McCarten/EPA

Chattanooga, Tennessee, February 4: Republican hopeful, former Arkansas Governor Mike Huckabee applauds actor Chuck Norris as he appears at a campaign stop for Huckabee Photograph: Mark Humphrey /AP

Santa Ana, California, February 4: Former U.S. President Bill Clinton campaigns for his wife Hillary at a rally Photograph: David McNew/Getty

East Rutherford, New Jersey, February 4: Robert De Niro turns out to support Obama at a rally Photograph: Emmanuel Dunnand /AFP

Atlanta, Georgia, February 4: A sign outside a hotel ballroom after Romney spoke at a rally Photograph: Erik S. Lesser/EPA

New York, February 4: McCain's campaign bus, "The Straight Talk Express" through Manhattan Photograph: Mario Tama/Getty

Chappaqua, New York, February 5: Hillary Clinton talks with reporters as her husband Bill stands in a voting booth Photograph: Justin Sullivan/Getty