Barack Obama, then junior United States senator from Illinois, announced his candidacy for president of the United States on February 10, 2007, in Springfield, Illinois. After winning a majority of delegates in the Democratic primaries of 2008, on August 23, leading up to the convention, the campaign announced that Senator Joe Biden of Delaware would be the vice presidential nominee. At the 2008 Democratic National Convention on August 27, Barack Obama was formally selected as the Democratic Party nominee for president of the United States in 2008. He was the first African American in history to be nominated on a major party ticket. On November 4, 2008, Obama defeated the Republican nominee, Senator John McCain of Arizona, making him the president-elect and the first African American elected president.

Obama was the third sitting U.S. senator, after Warren G. Harding and John F. Kennedy, to be elected president. Upon the vote of the Electoral College on December 15, 2008, and the subsequent certification thereof by a Joint Session of the United States Congress on January 8, 2009, Barack Obama was elected as president and Joe Biden as vice president, with 365 of 538 electors. He also became the first president to not be born in the contiguous United States, as he was born in Hawaii.