President Barack Obama has been formally sworn in for a second four-year term. Vice President Joe Biden also took the oath of office Sunday before Monday's public inauguration ceremony, to be witnessed by hundreds of thousands of people on the National Mall.
Obama took the oath just before noon in a ceremony lasting about half a minute in the oval-shaped White House Blue Room, with views of the executive mansion's South Lawn sweeping down to the Washington Monument.
With First Lady Michelle Obama, daughters Malia and Sasha, and a small group of reporters looking on, Supreme Court Chief Justice John Roberts administered the oath.
Obama shook Roberts hand, kissed his wife and children, and said to his family, "I did it."
President Barack Obama and first lady Michelle Obama waves as they walk down Pennsylvania Avenue near the White House during the Inauguration parade, Jan. 21, 2013.
The U.S. Army band marches down Pennsylvania Avenue en route to the White House during the Inaugural parade, Jan. 21, 2013.
President Barack Obama waves after his speech while Vice President Joe Biden applauds at the ceremonial swearing-in at the U.S. Capitol, Jan. 21, 2013.
President Barack Obama speaks at the ceremonial swearing-in at the U.S. Capitol during the 57th Presidential Inauguration in Washington, Jan. 21, 2013.
President Barack Obama, L, is sworn-in for a second term by Supreme Court Chief of Justice John Roberts, R, during his public inauguration ceremony at the U.S. Capitol in Washington, D.C., Jan. 21, 2013, while wife Michelle (L-R) and daughters Sasha and Malia look on.
Crowds of people gather on the mall to watch the swearing-in of U.S. President Barack Obama in Washington, January 21, 2013.
Khongorzul Battsengel, left, and Ariunbolor Davaatsogt both from Mongolia, take a picture of themselves as they wait for President Barack Obama in the 57th Presidential Inaugural Parade on Pennsylvania Ave. in Washington D.C., Jan. 21, 2013.
Spectators react on the National Mall during the 57th inauguration ceremonies for U.S. President Barack Obama and Vice President Joe Biden on the West front of the U.S. Capitol, in Washington, D.C., Jan. 21, 2013.
Vice President Joe Biden, left and President Barack Obama wait for their ceremonial swearing-in at the U.S. Capitol during the 57th Presidential Inauguration in Washington, Jan. 21, 2013.
People cheer on the National Mall during the ceremonial swearing-in ceremonies of U.S. President Barack Obama and Vice President Joe Biden on the West front of the U.S. Capitol, Jan. 21, 2013.
A woman listens on the National Mall during the 57th inauguration ceremonies on the West front of the U.S. Capitol, Jan. 21, 2013.
Spectators wave American flags on the National Mall in Washington, Jan. 21, 2013, before the start of President Barack Obama's ceremonial swearing-in ceremony during the 57th Presidential Inauguration.
Dr. Bernice King, center right, and Christine King Farris, left, the daughter and sister of Dr. Martin Luther King Jr., applaud while watching a broadcast of President Barack Obama's inauguration following the Dr. Martin Luther King Jr. holiday commemorative service at the Ebenezer Baptist Church in Atlanta, Jan. 21, 2013.
Members of the Lee University Festival Choir and PS 22 Chorus perform before the ceremonial swearing-in of President Barack Obama at the U.S. Capitol during the 57th Presidential Inauguration, Jan. 21, 2013.
President Barack Obama's daughters Malia Obama, left, and Sasha Obama arrive on the West Front of the Capitol in Washington, Jan. 21, 2013, for the president's ceremonial swearing-in.
President Barack Obama arrives at the ceremonial swearing-in at the U.S. Capitol during the 57th Presidential Inauguration in Washington, Jan. 21, 2013.
Secretary of State Hillary Clinton and former President Bill Clinton speak with former President Jimmy Carter at the ceremonial swearing-in for President Barack Obama at the U.S. Capitol in Washington, Jan. 21, 2013.
President Barack Obama arrives on the West Front of the Capitol in Washington, Jan. 21, 2013, for his ceremonial swearing-in ceremony during the 57th Presidential Inauguration.
Security lines Pennsylvania Avenue in Washington, Monday, Jan. 21, 2013, prior to the start of the 57th Presidential Inaugural Parade.
People wave at President Barack Obama and Vice President Joe Biden as their limousine passes Monday, Jan. 21, 2013, in Washington.
President Barack Obama and Democratic Senator from New York Chuck Schumer, the chairman of the Joint Congressional Committee on Inaugural Ceremonies, leave the White House on January 21, 2013 for the U.S. Capitol in Washington, D.C.
President Barack Obama supporters wave American flags on the National Mall in Washington, Jan. 21, 2013, prior to the start of the president's ceremonial swearing-in ceremony during the 57th Presidential Inauguration.
This was the seventh time in U.S. history a president has taken the oath on Sunday, before a public ceremony the following day. The U.S. Constitution requires a president's term to begin on January 20.
Obama used a Bible that belonged to his wife's grandmother, LaVaughn Delores Robinson.
In his public inauguration Monday at the U.S. Capitol, he will again lay his hand on the bible used by President Abraham Lincoln at his inauguration in 1861.
Obama will also use a second bible, once owned by the late civil rights leader Dr. Martin Luther King Jr. The ceremony occurs on the national holiday established to honor Dr. King.
This year also marks the 50th anniversary of the 1963 March on Washington for equal rights for African-Americans, and the 150th anniversary of President Lincoln's Emancipation Proclamation that initiated the process of freeing slaves in America.
President Obama and his family also attended a Sunday service at the Metropolitan African Methodist Episcopal Church, which has an important place in history for African-Americans.
Earlier, Vice President Biden took the oath at his official residence at the Naval Observatory in Washington, using a Biden family bible.
It was administered by Supreme Court Justice Sonia Sotomayor, and was the first time a Hispanic-American has done so.
The president and Biden also laid a wreath at the Tomb of the Unknowns at Arlington National Cemetery to honor fallen members of the military.
Obama begins his second term amid a mix of public optimism and pessimism about the economy, and the ability of leaders to put aside partisan bickering to prioritize progress on job creation and fixing fiscal problems.
The president's personal approval and likability ratings are high. Polls show a majority of Americans more optimistic about his second term. But fewer than half believe Obama and Republicans will be able to work together.
John Hudak is an expert in governance at the Brookings Institution. "The best solution right now is whatever he can get through Congress and is willing to sign, and the more he works with Congress under that heading, under that concept of executive - legislative relations, the more beneficial it will be in terms of addressing the real problems that we face," he said.
The official theme of Obama's second inaugural is "our people, our future". Specifics of his address on Monday are not known. Aides said he continued to make changes to the speech.
While he may make reference to political gridlock in Washington, a White House video released last week appeared to provide a hint of part of his overall message.
"This country has gone through some very tough times before, but we always come out on the other side," said the president. "This task of constantly perfecting our union, making it more fair and making sure that everybody in this country has a fair shot that if you work hard you can make it regardless of the circumstances of your birth, or what you look like, or where you come from, what God you pray to."
About three weeks will separate Obama's inaugural address on Monday, and his State of the Union Address on February 12.
He will use that speech to lay out specific policy objectives for his second term, with the economy, immigration reform, new gun control legislation and continuing the drawdown of U.S. combat troops from Afghanistan topping the agenda.