[139]
Decisions by Republican incumbent Peter Fitzgerald and his Democratic predecessor Carol Moseley Braun to not participate in the election resulted in wide-open Democratic and Republican primary contests involving 15 candidates.[140] In the March 2004 primary election, Obama won in an unexpected landslide—which overnight made him a rising star within the national Democratic Party, started speculation about a presidential future, and led to the reissue of his memoir, Dreams from My Father.[141] In July 2004, Obama delivered the keynote address at the 2004 Democratic National Convention,[142] seen by nine million viewers. His speech was well received and elevated his status within the Democratic Party.[143]
Obama's expected opponent in the general election, Republican primary winner Jack Ryan, withdrew from the race in June 2004.[144] Six weeks later, Alan Keyes accepted the Republican nomination to replace Ryan.[145] In the November 2004 general election, Obama won with 70 percent of the vote, the largest margin of victory for a Senate candidate in Illinois history.[146] He took 92 of the state's 102 counties, including several where Democrats traditionally do not do well.

