US Democratic presidential candidate Sen Barack Obama walks back to his campaign train at the Downingtown Station near Philadelphia Pennsylvania

 
US Democratic presidential candidate Sen Barack Obama walks back to his campaign train at the Downingtown Station near Philadelphia Pennsylvania
US Democratic presidential candidate Senator Barack Obama (D-IL) walks back to the train after a rally at the Downingtown Station near Philadelphia, Pennsylvania, April 19, 2008. REUTERS/Tim Shaffer (UNITED STATES) US PRESIDENTIAL ELECTION CAMPAIGN 2008 (USA)