The celebration of President Barack Obama's second inauguration was in full swing in Washington, D.C. on Sunday, a day before the public ceremony by the U.S. Capitol.

The 20th Amendment of the U.S. Constitution requires the president's term to start at noon on January 20, but because this year it fell on a Sunday, which is considered a legal holiday, there were two ceremonies this time.

Obama took the oath of office at 11:55 a.m. Sunday during a private event in the White House's Blue Room.

Standing alongside his wife, first lady Michelle Obama, and their two daughters Sasha and Malia, the president placed his hand on a Bible owned by the first lady's family and was administered the oath by Chief Justice John Roberts.

Vice President Joe Biden was officially sworn in to his second term earlier in the morning at his official residence, the Naval Observatory in Washington.

Supreme Court Justice Sonia Sotomayor, a native of the Bronx, administered the oath of office.

Between their ceremonies, both Biden and Obama headed to Arlington National Cemetery, where they both laid a wreath at the Tomb of the Unknowns.

Obama and Biden will recite their oaths of office again on Monday in a public ceremony on the U.S. Capitol steps, as hundreds of thousands of people look on in the National Mall.

The president will use a Bible that belonged to civil rights leader Dr. Martin Luther King Jr. and another one that belonged to President Abraham Lincoln.

"Barack Obama is continuing to evoke the symbolism of Lincoln as part of the mystique of his administration, but of course the inauguration celebration this year also falls on Martin Luther King Day," said Allan Lichtman of American University.

By Monday afternoon, Obama will have taken the presidential oath of office four times. Roberts misspoke the oath as he swore in Obama during his first inauguration in 2009, so Obama held a second swearing-in ceremony a few hours later.

Up to 1.8 million people attended Obama's first inauguration ceremony four years ago.

The last president to have his inauguration fall on a Sunday was Ronald Reagan in 1985.

After Obama makes his second inauguration speech Monday, he will take part in the traditional parade down Pennsylvania Avenue to the White House around 2:30 p.m.

Eight floats and 59 marching bands, cultural organizations and military groups, including New York's United War Veterans Council, are expected to be part of the parade.

Later, the Obamas will attend two official inaugural balls.

On Saturday night, the first lady and her daughters attended the Kids Inaugural Concert in Washington last night.

The event honored American military families and was live-streamed to military bases around the country.

Lawmakers Discuss Obama's Second-Term Agenda

Inaugural pageantry aside, Washington lawmakers are looking ahead at Obama's second-term agenda, including a focus on the deficit and passing the next budget.

The Democrat-controlled Senate hasn't passed a full budget since 2009.

Senator Charles Schumer said Democrats will pass a budget proposal this year, but Republicans said that is just the beginning of the process.

"You're going to need more revenues as well as more cuts to get the deficit down," Schumer said on NBC's "Meet The Press." "And I've talked to [Senate Majority] Leader [Harry] Reid, I've talked to budget chair [Senator Patty] Murray. We're going to do a budget this year and it's going to have revenues in it and our Republican colleagues better get used to that fact."

"I'm for cutting spending. So just passing a budget isn't quite enough but at least it's a step in the right direction," said Senator Roy Blunt, a Republican from Missouri.

Congress is also trying to figure out what to do when the government hits its borrowing limit soon.

Republicans appear to be willing to extend that borrowing authority for three more months, along with insisting on measures to cut spending.