This May 10, 2007, file photo shows David Plouffe, campaign manager for Democratic presidential hopeful Sen. Barack Obama, D-Ill., in his Chicago campaign headquarters. As the marathon Democratic primary campaign nears an end, Obama's staff is on the verge of vindicating its belief that the eloquent black freshman senator was a unique candidate who could win the Democratic nomination. The band of Obama loyalists who imagined that could happen have stunned even themselves with their success against Hillary Rodham Clinton. (AP Photo/Charles Rex Arbogast, File)