President Barack Obama was officially sworn into office on Sunday shortly before noon per constitutional mandate, in a small ceremony at the White House.
The small ceremony comes ahead of the glitzy Monday affair on the National Mall in Washington DC.
Chief Justice John Roberts, head of the US Supreme Court, administered the oath of office to the president, Reuters reported. He also swore Obama in in 2009.
The swearing-in, held in the White House Blue Room, took less than two minutes, according to the New York Times. Obama's wife and daughters were present.
This will be the third time Obama has recited the constitutional oath since he took office in 2008, although Obama will repeat it again during the Martin Luther King Day ceremony. A live stream of the ceremony will be on offer here at 11:55 AM, Eastern Time.
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Monday's public ceremony is expected to attract thousands of Americans to none-too-balmy Washington DC, where they will watch Obama deliver an address detailing his vision for his second official term.
An official program for the event is on offer here, and it will be widely televised. The Presidential Inaugural Committee will live-stream the Monday event at this link, as well as today's 11:55 AM official swearing-in.
Why is Obama being sworn in twice? It's a matter of both the calendar and constitutional law. According to the 20th Amendment to the US Constitution, Obama must begin his term at noon on January 20th.
Tradition is the reasoning behind the second event on Monday, after James Monroe decided back in 1821, after his Sunday swearing-in, that it would be better to hold the public event on a Monday.
The rationale? According to the US Government, it's because “courts and other public institutions were not open on Sunday.”
The Presidential Oath of Office may be important, but it's not very long: Obama must repeat "I do solemnly swear (or affirm) that I will faithfully execute the office of President of the United States, and will to the best of my ability, preserve, protect and defend the Constitution of the United States."
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Vice President Joe Biden was sworn on early Sunday morning at the Naval Observatory by Associate Justice Sonia Sotomayor, who he personally selected to deliver the oath — the fourth woman to do so in history.
Biden used the Biden Family Bible in the ceremony, which he's used since the first time he was sworn in as a Senator back in 1972. It's been in the family since 1893.
Here's video of the ceremony:
And a video of Obama's swearing in: