U.S. President Barack Obama attends the Nuclear Security Summit in the Hague, Netherlands, in March 2014. As Obama's second term nears its close, here's a look at some key moments of his administration. Sean Gallup/Getty Images

First lady Michelle Obama brushes specks from the coat of then-Sen. Obama in Springfield, Illinois, just before he announced his candidacy for President in February 2007. Their daughters Malia, left, and Sasha wait in the foreground. Pete Souza/Chicago Tribune/MCT/Getty Images

Obama appears on "Meet the Press" with Tim Russert, right, in Des Moines, Iowa, in November 2007. Eric Thayer/Getty Images for Meet the Press

Obama shakes hands with supporters after addressing a rally in Concord, New Hampshire, in January 2008. Chip Somodevilla/Getty Images

Obama gives a speech at the National Constitution Center in Philadelphia in March 2008. EMMANUEL DUNAND/AFP/Getty Images

Obama speaks at the 2008 Democratic National Convention in Denver. STAN HONDA/AFP/Getty Images

Obama stands on stage in Chicago with his family after winning the presidential election on November 4, 2008. Joe Raedle/Getty Images

Obama poses in the Oval Office with several former U.S. Presidents in January 2009. From left are George H. W. Bush, Obama, George W. Bush, Bill Clinton and Jimmy Carter. Mark Wilson/Getty Images

Obama is sworn in by Chief Justice John Roberts as the 44th President of the United States on January 20, 2009. Chip Somodevilla/Getty Images

As retired military officers stand behind him, Obama signs an executive order to close down the detention center at Guantanamo Bay, Cuba, in January 2009. Mark Wilson/Getty Images

Obama and Vice President Joe Biden look at solar panels as they tour the solar array at the Denver Museum of Nature and Science on February 17, 2009. That same day, Obama signed the American Recovery and Reinvestment Act. JIM WATSON/AFP/Getty Images

A soldier hugs Obama during his surprise visit to Camp Victory just outside Baghdad, Iraq, in April 2009. MANDEL NGAN/AFP/Getty Images

Obama bends over so the son of a White House staff member can pat his head during a visit to the Oval Office in May 2009. The boy wanted to know if Obama's hair felt like his. Pete Souza/White House

Obama kisses Sonia Sotomayor's cheek after announcing her as his nominee for Supreme Court justice in May 2009. Joshua Roberts/Bloomberg via Getty Images

Palestinian security forces in Jenin, West Bank, listen to Obama speak from Cairo University in Egypt in June 2009. The Palestinian Authority hailed as a "good beginning" Obama's speech to the Muslim world in which he reiterated his support for a Palestinian state. SAIF DAHLAH/AFP/Getty Images

Obama and the first lady meet with Pope Benedict XVI in Vatican City in July 2009. Pete Souza/The White House via Getty Images

Obama hosts the Apollo 11 astronauts -- from left, Edwin "Buzz" Aldrin, Michael Collins and Neil Armstrong -- in the Oval Office on July 20, 2009. It was the 40th anniversary of the moon landing. Chip Somodevilla/Getty Images

Police Sgt. James Crowley, second right, of Cambridge, Massachusetts, speaks with Harvard Professor Henry Louis Gates Jr., second left, alongside Obama and Biden as they share beers on the South Lawn of the White House in July 2009. The so-called Beer Summit was held after Crowley arrested Gates at his own home, which sparked tensions and racial furor. SAUL LOEB/AFP/Getty Images

Obama salutes during the transfer of Sgt. Dale R. Griffin at Dover Air Force Base in Dover, Delaware, in October 2009. Obama traveled to the base to meet the plane carrying the bodies of 18 U.S. personnel killed in Afghanistan. SAUL LOEB/AFP/Getty Images

Obama walks along the Great Wall of China in November 2009. SAUL LOEB/AFP/Getty Images

Obama delivers a speech after receiving the Nobel Peace Prize in Oslo, Norway, in December 2009. JEWEL SAMAD/AFP/Getty Images

Obama and former Presidents Clinton and George W. Bush walk to the White House Rose Garden to speak about relief efforts for earthquake-stricken Haiti in January 2010. Mark Wilson/Getty Images

First daughters Sasha and Malia Obama play in the snow with their father after a snowstorm hit Washington in February 2010. Pete Souza/White House

Obama's signature on the Affordable Care Act is seen at the White House in March 2010. Chuck Kennedy/White House

Obama throws out the opening pitch before a baseball game between the Philadelphia Phillies and the Washington Nationals in April 2010. G Fiume/Getty Images

Obama and his daughter Sasha swim in Panama City Beach, Florida, in August 2010, to encourage people to come back to the Gulf Coast after a devastating oil spill. Pete Souza/The White House via Getty Images

Obama laughs as he makes a statement on his birth certificate in April 2011. Obama said he was amused over conspiracy theories about his birthplace, and he said the media's obsession with the "sideshow" issue was a distraction in a "serious time." JEWEL SAMAD/AFP/Getty Images

Obama, Biden, Secretary of State Hillary Clinton and members of the national security team receive live updates on the mission to capture or kill Osama bin Laden on May 1, 2011. Pete Souza/The White House via Getty Images

U.S. Marines watch from Afghanistan as Obama announces the death of bin Laden on May 2, 2011. BAY ISMOYO/AFP/Getty Images

Obama enjoys a pint of Guinness in his ancestral home of Moneygall, Ireland, in May 2011. Irish Government/Pool/Getty Images

Obama and the first lady meet with Britain's Prince William and Catherine, Duchess of Cambridge, at Buckingham Palace in May 2011. Charles Dharapak/WPA Pool/Getty Images

Obama and Missouri Gov. Jay Nixon walk together in May 2011 during a tour of the tornado devastation in Joplin, Missouri. Joe Raedle/Getty Images

Obama delivers remarks to troops and military families at Fort Bragg, North Carolina, on December 14, 2011, marking the exit of U.S. soldiers from Iraq. JIM WATSON/AFP/Getty Images

Obama pays for a dog toy as he shops with his dog Bo at a PetSmart in Alexandria, Virginia, in December 2011. Kevin Dietsch/Pool/Getty Images

Obama sits on the famed Rosa Parks bus at the Henry Ford Museum in Dearborn, Michigan, in April 2012. Pete Souza/White House Photo via Getty Images

British Prime Minister David Cameron, Obama, German Chancellor Angela Merkel and others watch the overtime shootout of the Champions League final between Chelsea and Bayern Munich in a conference room at Camp David, Maryland, during a G-8 Summit in May 2012. Pete Souza/The White House via Getty Images

Obama sits in his chair during a Cabinet meeting in July 2012. This image was tweeted by his official Twitter account in August 2012 in response to Clint Eastwood's "empty chair" speech at the Republican National Convention. The tweet simply said, "This seat's taken." Pete Souza/White House

Obama casts a shadow in this picture as he accepts the 2012 Democratic nomination for President during the final day of the Democratic National Convention in September 2012. Win McNamee/Getty Images

Obama and Republican presidential candidate Mitt Romney participate in the first presidential debate of the 2012 election. SAUL LOEB/AFP/Getty images

Obama celebrates on stage in Chicago after defeating Romney on Election Day in 2012. JEWEL SAMAD/AFP/Getty Images

Obama pauses during his speech at a memorial service for the victims of the Sandy Hook Elementary School massacre in December 2012. MANDEL NGAN/AFP/Getty Images

Hundreds of thousands gather at the U.S. Capitol building as Obama is inaugurated for his second term on January 21, 2013. Charles Ommanney/Reportage by Getty Images

Israeli President Shimon Peres, left, and Prime Minister Benjamin Netanyahu, right, stand with Obama after Obama arrived in Tel Aviv, Israel, in March 2013. MANDEL NGAN/AFP/Getty Images

Obama adjusts an umbrella held by a Marine during a White House news conference with Turkish Prime Minister Recep Tayyip Erdogan in May 2013. Charles Dharapak/AP

Jay Leno interviews Obama on "The Tonight Show" in August 2013. Paul Drinkwater/NBC/NBCU Photo Bank via Getty Images

White House press secretary Jay Carney fields questions from reporters during a daily press briefing at the White House in September 2013. Obama had just pushed for congressional approval for limited military strikes against the Syrian government. Chip Somodevilla/Getty Images

Actor and comedian Zach Galifianakis interviews Obama during his appearance on "Between Two Ferns," a digital video series with a laser focus on reaching people aged 18 to 34. The President urged young people to sign up for his new health care plan in the video posted on the website Funny or Die. Funny Or Die/AP

Obama walks to the Oval Office on August 7, 2014, the same day he announced the beginning of airstrikes on ISIS. SAUL LOEB/AFP/Getty Images

Obama speaks to the nation about normalizing diplomatic relations with Cuba in December 2014. Doug Mills/Pool/Getty Images

From left, House Majority Leader Kevin McCarthy, House Minority Leader Nancy Pelosi and House Speaker John Boehner listen as Obama speaks during a meeting in the Cabinet Room of the White House on January 13, 2015. Alex Wong/Getty Images

Obama responds to a heckler who interrupted his speech during a White House reception for LGBT Pride Month in June 2015. SAUL LOEB/AFP/Getty Images

Obama cries in January 2016 as he delivers a statement on his executive action to reduce gun violence. JIM WATSON/AFP/Getty Images

Cuban President Raul Castro tries to lift up Obama's arm at the end of a joint news conference in Havana, Cuba, in March 2016. Castro hailed Obama's opposition to a long-standing economic "blockade," but said it would need to end before ties between the two countries are fully normalized. NICHOLAS KAMM/AFP/Getty Images

Obama visits Prince William, Duchess Catherine and their son, Prince George, during a trip to London in April 2016. Kensington Palace/PA Wire via Getty Images