
Democratic presidential hopeful, Sen. Barack Obama D-Ill., speaks during a rally at the Corn Palace in Mitchell, S.D. Sunday, June 1, 2008.
(AP Photo/Chris Carlson)

Democratic presidential hopeful, Sen. Barack Obama D-Ill., speaks during a rally at the Corn Palace in Mitchell, S.D. Sunday, June 1, 2008.
(AP Photo/Chris Carlson)

US Democratic presidential candidate and US Senator Barack Obama (D-IL) greets supporters after speaking in Mitchell, South Dakota June 1, 2008. REUTERS/Rick Wilking (UNITED STATES) US PRESIDENTIAL ELECTION CAMPAIGN 2008
(USA)

US Democratic presidential candidate and Senator Barack Obama (D-IL) speaks in Mitchell, South Dakota June 1, 2008. REUTERS/Rick Wilking (UNITED STATES) US PRESIDENTIAL ELECTION CAMPAIGN 2008
(USA)

US Democratic presidential candidate and Senator Barack Obama (D-IL) speaks in Mitchell, South Dakota June 1, 2008. REUTERS/Rick Wilking (UNITED STATES) US PRESIDENTIAL ELECTION CAMPAIGN 2008
(USA)