(CNN) - The 538 members of the Electoral College gathered in each of the 50 states and the District of Columbia on Monday to exercise their constitutional prerogative and cast their votes for president and vice president.
While Obama won 365 electoral votes on Election Night, compared to 173 for McCain, there is no constitutional provision or federal law requiring electors to vote for the candidate who won the popular vote in their states.
Twenty-six states and the District of Columbia have passed laws requiring electors to back the winner of the statewide popular vote, but the Supreme Court has never specifically ruled on the question of whether such requirements are constitutional.
According to the National Archives, a "faithless elector" has never been prosecuted for refusing to vote in accordance with his or her state's popular vote.
There is no chance, however, that the electors will overturn Barack Obama's November 4 victory.
Over the course of American electoral history, more than 99 percent of electors have voted as pledged. Presidential electors are almost always loyal partisan activists chosen by state parties or presidential campaigns as a reward for their political service.
In those rare recent circumstances in which an elector has refused to vote for his or her party's presidential nominee, the elector has instead usually chosen to either abstain or vote for another member of the same party.
Most recently, for example, a 2004 Democratic elector in Minnesota supported vice presidential nominee John Edwards for president, instead of presidential nominee John Kerry.
A joint session of Congress - presided over by outgoing Vice President Dick Cheney - will be held on January 8 to count the electoral votes from every state and the District of Columbia.