U.S. Senator, 2005–2008

Obama was sworn in as a senator on January 4, 2005.Obama was the fifth African-American Senator in U.S. history, and the third to have been popularly elected. He is the only Senate member of the Congressional Black Caucus. CQ Weekly, a nonpartisan publication, characterized him as a "loyal Democrat" based on analysis of all Senate votes in 2005–2007, and the National Journal ranked him as the "most liberal" senator based on an assessment of selected votes during 2007. In 2005 he was ranked sixteenth, and in 2006 he was ranked tenth. In 2008, Congress.org ranked him as the eleventh most powerful Senator. Obama announced on November 13, 2008 that he would resign his senate seat on November 16, 2008, before the start of the lame-duck session, to focus on his transition period.This enabled him to avoid the conflict of dual roles as President-elect and Senator in the lame duck session of Congress, which no sitting member of Congress had faced since Warren Harding. His immediate successor will be named by Illinois Governor Rod Blagojevich.