US Democratic presidential candidate Senator Barack Obama (D-IL) (R) and his running mate Sen. Joe Biden (D-DE), acknowledge supporters as former Democratic presidential candidate Sen. Hillary Clinton (D-NY) is pictured on a monitor above them, at the 2008 Democratic National Convention in Denver, Colorado, August 27, 2008. Democrats nominated Senator Barack Obama (D-IL) on Wednesday as their presidential candidate in a historic first for a black American, sending him into battle against Republican John McCain. REUTERS/Brian Snyder (UNITED STATES) US PRESIDENTIAL ELECTION CAMPAIGN 2008 (USA)