US Democratic presidential candidate Illinois Senator Barack Obama signs a wind turbine blade during a tour of Gamesa Wind Corporation, a wind turbine producer, in Faireless Hills, Pennsylvania, on March 11, 2008. Mississippi headed to the polls Tuesday as Democrat Barack Obama launched a withering assault on the foreign policy boasts of his White House adversary Hillary Clinton. Getty Images logo Getty Images 51 months ago

US Democratic presidential candidate Illinois Senator Barack Obama signs a wind turbine blade during a tour of Gamesa Wind Corporation, a wind turbine producer, in Faireless Hills, Pennsylvania, on March 11, 2008. Mississippi headed to the polls Tuesday as Democrat Barack Obama launched a withering assault on the foreign policy boasts of his White House adversary Hillary Clinton.