WASHINGTON: Barack Obama will Sunday be sworn in to shoulder the power and burden of the US presidency for a second term, launching two days of inaugural rituals darkened by domestic discord and crises abroad.

Democrat Obama, 51, will swear to faithfully execute the office of president at a low-key ceremony at 11:55 am (1655 GMT) in the Blue Room of the White House, to comply with the US Constitution, which dictates his first term ends at noon on January 20.

He will use a bible belonging to First Lady Michelle Obama's grandmother.

Vice President Joe Biden will be sworn in during a separate ceremony Sunday morning at the Naval Observatory.

In a tradition honored when that date falls on a Sunday, Obama will repeat the oath in a time-honored public ceremony on Monday, and deliver his inaugural address to Americans, and the watching world, outside at a chilly US Capitol.

Obama's second inauguration, which comes courtesy of an election win over Republican Mitt Romney in November, lacks the hope and history which pulsated through his swearing in as the first black American president in 2009.

Since then, a graying Obama has been battered by a weak economic recovery, failed to meet hugely elevated expectations for his presidency and waged a political war of attrition Republicans, which often slides into the gutter.

He begins anew with several fierce budget battles looming in Congress, and with his "Yes we Can" rhetoric soured by sarcasm over the blocking tactics of Republicans in the partisan brouhaha paralyzing government in Washington.

While polls show Obama's approval ratings above 50 percent -- far higher than the reviled Congress, they also indicate that many Americans, wearied by a stop-start recovery, doubt their country is headed in the right direction.

Abroad, the US confrontation with Iran is fast headed to a critical point with the specter of military action becoming ever more real, the longer diplomacy over Tehran's nuclear program is stuck in neutral.

Recent terror strikes which killed Americans in Benghazi and Algeria meanwhile call into question Obama's election year soundbite that "Al-Qaeda is on the run" despite the killing of Osama bin Laden in Pakistan.

Increasing muscle flexing by China and rising tensions in contested waters with its neighbors, as well as North Korea's nuclear belligerence, will meanwhile test the president's signature pivot of US diplomacy to Asia.

As he raises his right hand, 224 years after George Washington took the first oath of office to lead a new nation, Obama also knows that for second term presidents, power quickly wanes and political potholes await.

The second term "curse" often strikes: Richard Nixon resigned, Bill Clinton was impeached, George W. Bush's image was shattered by Iraq and Hurricane Katrina and Ronald Reagan's legacy was marred by the Iran-Contra scandal.

Obama has already said that he will root his second term on the crusade to build a more equitable economy which powered his triumph over multi-millionaire Romney.

"I intend to carry out the agenda that I campaigned on, an agenda for new jobs, new opportunity and new security for the middle class," Obama said last week.

After being sworn in surrounded by close family, Obama will put the finishing touches on his inaugural address.

Aides have offered few previews of what he will say on Monday, though such occasions offer the chance for presidents to stress national unity, and to bind wounds of the kind of acrimonious elections like the one Obama won in 2012.

Obama has been seen with yellow legal pads full of ideas for his speech, which will likely be high on poetry but low on policy: his State of the Union Address on February 12 will flesh out his agenda.

But the president will have a message for allies and enemies abroad, and could shape the political ground for top agenda priorities including immigration and energy reform and new gun control laws.

After Monday's solemn ceremony will come celebration, as Obama returns to the White House down a parade route lined with crowds, before a night of glittering inaugural balls -- though the festivities have been trimmed in recognition of the tough times many Americans are still enduring.

On Saturday, Obama and his wife Michelle grabbed paintbrushes for an inaugural day of service at a Washington DC school.

The president, wearing khaki trousers and a button down shirt, and the first lady, in a purple shirt and black leggings, helped stain a bookshelf along with two members of a group that works to keep children in school.

Obama later joked that "Michelle said I did a fine job."

There has been an immense security build-up ahead of the inauguration, with cameras and barricades covering much of the route leading up to the Capitol. Thousands of police will also fan the area on Monday: several at each street corner.