Oprah Winfrey's endorsement of Senator Barack Obama was one of the most widely covered and studied developments of the 2008 presidential campaign, as she has been described as the most influential woman in the world.[1][2][3] Winfrey first endorsed Senator Obama in September 2006 before he had even declared himself a candidate. In May 2007 Winfrey made her official endorsement of candidate Obama, and in December 2007, she made her first campaign appearances for him. Two economists estimate that Winfrey's endorsement was worth over a million votes in the Democratic primary race[4] and that without it, Obama would have received fewer votes.[5] Then-Governor of IllinoisRod Blagojevich claimed that the endorsement was so significant in making Obama president-elect that he considered offering Obama's former seat in the Senate to Winfrey.[6]