Hard choices ahead for America but ‘prospects are limitless’

But the president said every citizen deserved a basic measure of security and dignity, and he held up Medicare, Medicaid and Social Security as commitments that strengthen the country.

Speaking in his inaugural address at the US Capitol, Mr Obama said he rejected the belief that the country must choose between caring for the generation that built the country or investing in the generation that will build the future.

Struggles with Republicans over reducing the deficit and paring back costly entitlement programmes loom for him in his second term.

Mr Obama promised to respond to the “threat of climate change” and lead the way on renewable energy sources.

And he declared that a decade of war was ending, the nation’s economy was recovering and “America’s possibilities are limitless”.

“My fellow Americans, we are made for this moment, and we will seize it, so long as we seize it together,” he said, moments after taking the oath of office.

Trumpets blew and cannon fired as the country watched the president take the oath of office as the world’s most powerful elected leader.

Mr Obama’s address touched on the broad gifts that bring the country together, and pointed to the work ahead, “the realities of our time”.

He was officially sworn in yesterday, as required by law, but the glitter of Inauguration Day – the parade down Pennsylvania Avenue toward the White House, the night of balls, the ceremonial beginning of a new four-year presidential term – still enlivened staid Washington.

The celebration was pushed to yesterday because January 20 fell on a Sunday this year. That placed the grand ceremony on the US holiday marking the birthday of revered civil rights leader Martin Luther King.

Mr Obama, the politician who rose improbably from a history as a community organiser in Chicago and a professor of constitutional law to the pinnacle of power, faces a nation riven by partisan disunity, a still-weak economy and an array of challenges abroad.

The president also faces a less charmed standing on the world stage, where expectations for him had been so high four years ago that he was given the Nobel Peace Prize just months into his presidency.

The president, First Lady Michelle Obama and daughters Sasha and Malia began the day at St. John’s Episcopal church, which was built in 1812 and is known as the church of presidents. Mr Obama later had coffee at the White House with congressional leaders, who play major roles in how the country is governed.

The events had less of the effervescence of four years ago, when the 1.8 million people packed into central Washington knew they were witnessing history. Mr Obama is now older, greyer and more entrenched in the politics he once tried rise above. Officials said crowds were about half what they were four years ago.

Mr Obama was expected to follow the recent tradition of walking at least part of the way back to the White House, surrounded by cheers.

As he enters his second term, Americans increasingly see him as a strong leader, someone who stands up for his beliefs and is able to get things done, according to a survey by the Pew Research Centre for the People & the Press.

When the partying is over it will be back to business for a president who is leading a nation that is, perhaps, as divided as at any time since the Civil War 150 years ago. That conflict put down a rebellion by southern states and ended slavery.

Mr Obama referred to the Stonewall gay-rights riots in his address, classing them as a civil rights watershed along with key moments in the struggles for blacks and women.

The president said the truth that all are created equal guides us today “just as it guided our forebears through Seneca Falls, and Selma, and Stonewall.”

The Stonewall riots happened in New York in 1969 when patrons at a gay bar reacted to police harassment, and the events helped found the modern gay-rights movement.

Mr Obama, who has become increasingly outspoken in favour of gay rights and same-sex marriage, also said the nation’s journey is not complete “until our gay brothers and sisters are treated like anyone else under the law.”

David Cameron offered his congratulations via Twitter after Mr Obama delivered his inaugural address in Washington.