Barack Obama is sworn in as 44th US president by Chief Justice John Roberts beside wife Michelle on January 20, 2009 at the Capitol in Washington, DC.

President Barack Obama and first lady Michelle Obama dance at the Commander in Chief Inaugural Ball at the National Building Museum in Washington, Jan. 20, 2009.

President Barack Obama and Secretary of State Hillary Rodham Clinton speak together sitting at a picnic table, on the South Lawn of the White House, May 9, 2009. ( White House/Pete Souza)

President Barack Obama greets troops after delivering remarks at Fort Bliss in El Paso, Texas, Aug. 31, 2012. (White House/Pete Souza)

President Barack Obama hugs Donna Vanzant, the owner of North Point Marina, as he tours damage from Hurricane Sandy in Brigantine, N.J., Oct. 31, 2012. (White House/Pete Souza)

President Barack Obama and Prime Minister David Cameron of the United Kingdom stand during the playing of the national anthem during the Official Arrival Ceremony on the South Lawn, March 14, 2012. (White House/Pete Souza)

President Barack Obama looks at the Nobel Peace Prize medal for the first time at the Norwegian Nobel Institute in Oslo, Norway. December 10, 2009. (White House/Pete Souza)

President Barack Obama, first lady Michelle Obama, daughters Malia, right, and Sasha walk from the White House to St. John's Episcopal Church for Easter service in Washington Sunday, April 8, 2012.

President Barack Obama gestures as speaks at a campaign event at Cornell College, Wednesday, Oct. 17, 2012, in Mt. Vernon, Iowa.