Washington - President Barack Obama will urge his divided nation to unite around common values on Monday, launching his second term with a plea for ideological foes to unpick America's ugly political deadlock.
Obama, sworn in for four more years in a private ceremony on Sunday, will repeat the oath of office before a crowd of thousands wrapped up against the chill at the white-domed Capitol building, which is draped in huge US flags.
After Obama spent an exhausting first term battling the worst economic storm in decades and waging partisan warfare with Republicans, his second inauguration lacks the historic and hopeful promise of the first in 2009.
Yet Obama, aged 51, has a legacy to defend, including a historic healthcare law and a retrenchment from draining wars abroad, and he is vowing to make good on the promise of a fairer economy, which anchored his re-election win.
He signalled late on Sunday, at a reception for supporters, that he would dwell on the "common good" and the "goodness, the resilience, neighbourliness, the patriotism", of Americans when he gives his address for history on Monday.
"What we are celebrating is not the election or the swearing in of the president, what we are doing is celebrating each other and celebrating this incredible nation that we call home," Obama said.
"And after we celebrate, let's make sure to work as hard as we can to pass on an America that is worthy not only of our past, but also of our future."
Obama's senior advisor David Plouffe said on Sunday that the president will ask Americans in his inaugural address to remember what unites them, rather than political divisions which have split the country down the middle.
"He is going to talk about how our founding principles and values can still guide us in today's modern and changing world," Plouffe said on the ABC News show This Week.
"He is going to say that our political system does not require us to resolve all of our differences or settle all of our disputes, but it is absolutely imperative that our leaders try and seek common ground."
Obama took the oath of office on Sunday to comply with the US Constitution, which dictates his first term ends at noon on 20 January.
Tradition states that when that date falls on a Sunday, a private swearing-in is followed the next day by public festivities, including the second oath taking, the address, parade and glittering inaugural balls.
'I did it'
Obama, with a slight smile, took the oath with his right hand raised, and his left on a family Bible held by his wife Michelle, wearing a blue dress, to match the decor of the oval White House Blue Room hosting the ceremony.
Chief Justice John Roberts, who stumbled when swearing in Obama to open his first term in 2009, slowly read each line of the oath out loud, before the president repeated phrases first intoned by George Washington, 224 years ago.
Watched over by portraits of former presidents including Thomas Jefferson and John Adams, Obama hugged his wife and children Malia, aged 14, and Sasha, aged 11, before quipping: "I did it" to his youngest daughter.
After a tumultuous first term, Obama's status as the first African American president in a nation born on a racial fault line almost seems like an afterthought now - perhaps a sign of progress.
But poignantly, Obama will takes his second, second term oath of office on Martin Luther King day, the federal holiday marking the civil rights pioneer's birthday.
He will rest his left hand on a Bible once owned by King, and another which once belonged to his hero Abraham Lincoln, the president who ended slavery.
And in another historic echo, Obama will become the second president to be sworn in four times - thanks to the Roberts stumble in 2009 and his double oath duty this year, joining Democratic icon Franklin Roosevelt.
Hours before Obama leaves the White House and journeys 2.5km to the Capitol, police and the Secret Service tightened a security vice, with high fences encircling the presidential mansion and parade route in a secure ring of steel.
Fewer than the two million spectators who saw Obama inaugurated in 2009 were expected on Monday, though there was still a festive hour among tourists milling around the White House.
Obama, aged 51, will embark on a second term at a time of deep partisan division in Washington, and will face foreign crises testing his legacy, including Iran's nuclear program and resurgent Islamist militancy in North Africa.
He begins anew with budget battles looming in Congress, and his "Yes We Can" rhetoric soured by sarcasm over the blocking tactics of Republicans in Congress.
Abroad, the US confrontation with Iran is fast-headed to a critical point with the spectre of military action becoming ever more real the longer diplomacy over Tehran's nuclear program remains stuck in neutral.
And terror strikes that killed Americans in Benghazi and Algeria call into question Obama's election year sound bite that "Al-Qaeda is on the run", despite the killing of Osama bin Laden in Pakistan in 2011.