Conceding disappointments during his presidency yet offering vigorous encouragement for the nation’s future, outgoing US President Barack Obama has issued an emotional defence of his vision to Americans facing a moment of anxiety and a dramatic change in leadership.

Mr Obama’s valedictory speech in his hometown of Chicago was a public meditation on the trials and triumphs, promises kept and promises broken that made up his eight years in the White House.

Arguing his faith in America had been confirmed, Mr Obama said he ends his tenure inspired by America’s “boundless capacity” for reinvention, and declared: “The future should be ours.”

His delivery was forceful for most of his speech, but by the end he was wiping away tears as the crowd embraced him one last time.

He thanked thousands of supporters and reaffirmed his belief in the power of change, harkening back to the message of his first campaign for president in 2008.

Reflecting on the corrosive recent political campaign, he said “potential will be realised only if our democracy works”.

“Only if our politics reflects the decency of our people. Only if all of us, regardless of our party affiliation or particular interest, help restore the sense of common purpose that we so badly need right now,” he said.

Mr Obama made no direct mention of Republican Donald Trump, who will replace him in just 10 days.

But when he noted the imminence of that change and the crowd began booing, he responded: “No, no, no, no, no.” One of the nation’s great strengths, he said, “is the peaceful transfer of power from one president to the next”.

Earlier, as the crowd of thousands chanted “four more years,” he simply smiled and said: “I can’t do that.”

‘Show up. Dive in. Stay at it’

Barack Obama’s return to Chicago was a bittersweet reunion bringing together Obama loyalists and staffers. Photo: AP

Mr Obama said protecting the nation’s way of life is the job of citizens as well as the military.

He said “democracy can buckle when we give in to fear”.

“If you’re disappointed by your elected officials, grab a clipboard, get some signatures and run for office yourself,” he said.

“Show up. Dive in. Stay at it. Sometimes you will win. Sometimes you will lose.”

Mr Obama also made a reference to Mr Trump’s campaign calls for a temporary ban on Muslim immigration to the United States.

The outgoing President said he rejects discrimination against Muslim Americans, and drew cheers for saying they are “just as patriotic as we are”.

Barack Obama is joined by his daughter Malia and First Lady Michelle Obama after giving his farewell address. Photo: AP

During the speech, Mr Obama took a moment to thank his wife and his daughters Malia and Sasha for sacrificing for his political dreams.

He noted that his partner for the past 25 years took on a role she did not want and made it her own with “grace and grit and style and good humour”.

“A new generation sets its sights higher because it has you as a role model,” he said.

“So you have made me proud and you have made the country proud.”

He also thanked his staff and supporters, and said choosing Mr Biden to be his Vice-President was the first and best choice he made.

Mr Obama said Mr Biden — “the scrappy kid from Scranton who became Delaware’s favourite son” — has not only been a great Vice-President during the past eight years, but he also was an unexpected gift.

The outgoing President said that in Mr Biden, he gained a brother, and that the friendship had been “one of the great joys” of his life.

Mr Obama wrapped up by saying it had been an honour to serve America.

“For now, whether you’re young or young at heart, I do have one final ask of you as your President — the same thing I asked when you took a chance on me eight years ago,” he said.

“I am asking you to believe. Not in my ability to bring about change — but in yours.

I am asking you to hold fast to that faith written into our founding documents; that idea whispered by slaves and abolitionists; that spirit sung by immigrants and homesteaders and those who marched for justice; that creed reaffirmed by those who planted flags from foreign battlefields to the surface of the moon; a creed at the core of every American whose story is not yet written:

“Yes we can. Yes we did. Yes we can.”

Obama’s return to Chicago steeped in nostalgia

Soon Mr Obama and his family will exit the national stage to be replaced by Mr Trump, a man Mr Obama had stridently argued poses a dire threat to the nation’s future.

His near-apocalyptic warnings throughout the campaign have cast a continuing shadow over his post-election efforts to reassure Americans anxious about the future.

Indeed, much of what Mr Obama accomplished over the past eight years — from health care overhaul and environmental regulations to his nuclear deal with Iran — could potentially be upended by Mr Trump. So even as Mr Obama seeks to define what his presidency meant for America, his legacy remains in question.

Mr Obama touched down in Chicago, marking his 445th trip on the presidential aircraft. Photo: AP

Even as Mr Obama said farewell to the nation — in a televised speech of just under an hour — the anxiety felt by many Americans about the future was palpable, and not only in the Chicago convention centre where he stood in front of a giant presidential seal.

The political world was reeling from new revelations about an unsubstantiated report that Russia had compromising personal and financial information about Mr Trump.

Steeped in nostalgia, Mr Obama’s return to Chicago was less a triumphant homecoming and more a bittersweet reunion bringing together Obama loyalists and loyal staffers, many of whom have long since left Obama’s service, moved on to new careers and started families.

Even the final trip on the presidential aircraft was a moment tinged with wistfulness.

It was Mr Obama’s 445th trip on the presidential aircraft, a perk he has said he will miss when he leaves office.

Seeking inspiration, Mr Obama’s speechwriters spent weeks poring over Obama’s other momentous speeches, including his 2004 keynote at the Democratic National Convention and his 2008 speech after losing the New Hampshire primary to Hillary Clinton.

They also revisited his 2015 address in Selma, Alabama, that both honoured America’s exceptionalism and acknowledged its painful history on civil rights.

After returning to Washington, Mr Obama will have less than two weeks before he accompanies Mr Trump in the presidential limousine to the Capitol for the new president’s swearing-in.

After nearly a decade in the spotlight, Mr Obama will become a private citizen, an elder statesman at 55. He plans to take some time off, write a book — and immerse himself in a Democratic redistricting campaign.

-with AP