Then Democratic presidential candidate Barack Obama addresses supporters during his election night rally at Grant Park in Chicago, Illinois, on November 5, 2008
Washington (AFP) - Barack Obama closes the book on his presidency Tuesday, with a farewell speech in Chicago that will try to lift supporters shaken by Donald Trump's shock election.
Obama's last trip on Air Force One is a pilgrimage to his adoptive hometown, where he will address a sell-out crowd not far from where he delivered his victory speech eight years ago.
"I first came to Chicago when I was in my early twenties, still trying to figure out who I was; still searching for a purpose to my life," Obama is expected to tell Chicagoans, according to advance excerpts of his speech.
"This is where I learned that change only happens when ordinary people get involved, get engaged, and come together to demand it."
"After eight years as your president, I still believe that."
Diehard fans -- many African Americans -- have braved Chicago's frigid winter to collect free tickets, which now sell for upwards of $1,000 a piece on Craigslist.
Joined by First Lady Michelle Obama, Vice President Joe Biden and his wife Jill, Obama's trip would be a sentimental walk down memory lane, were it not slap-bang in the middle of a tumultuous presidential handover.
Trump has smashed conventions, vowed to efface Obama's legacy and hurled personal insults left and right.
The 2016 election campaign has raised serious questions about the resilience of US democracy.
In a virtually unprecedented move, US intelligence has accused the Kremlin of seeking to tip the electoral scales in Trump's favor.
Democrats, cast into the political wilderness with the loss of the White House, the Senate and the House of Representatives plus a majority of statehouses, are struggling to regroup.
- 'True to him' -
With an approval rating hovering around 55 percent, according to a Quinnipiac University poll, Obama will hope to steel them for new battles ahead.
Some 51 percent of Americans polled believe that Trump is doing a bad job as president-elect.
Obama's lead speechwriter Cody Keenan said the address will be about a vision for where the country should go.
"It's not going to be like an anti-Trump speech, it's not going to be a red meat, rabble rousing thing, it will be statesman-like but it will also be true to him," Keenan told AFP. "It will tell a story."
As Obama put it: "Over the course of my life, I've been reminded time and again that change can happen -- that ordinary people can come together to achieve extraordinary things."
"And I've seen that truth up close over these last eight years."
- Life after White House -
Trump's unorthodox politics has thrown 55-year-old Obama's transition and post-presidency plans into flux.
Having vowed a smooth handover of power, Obama finds himself being increasingly critical of Trump as he prepares to leave office on January 20.
After that there will still be a holiday and an autobiography, but Obama could find himself being dragged backed into the political fray if Trump were to enact a Muslim registry or deport adults brought to the United States years ago by their parents.
Having vowed to take a backseat in politics, Obama's second act could yet be as politically engaged as Jimmy Carter -- whose post-presidency has remade his image as an elder statesman.
Many Obama aides who had planned to take exotic holidays or launch coffer-replenishing forays into the private sector are also reassessing their future and mulling a return to the political trenches.
Obama's foundation is already gearing up for a quasi-political role -- funneling idealistic youngsters into public life.
- Presidential precedent -
Presidents since George Washington have delivered a farewell address of sorts.
Washington's final 7,641-word message -- which is still read once a year in the Senate by tradition -- contained warnings about factionalism and interference by foreign powers that seem oddly prescient.
But speechwriter Keenan sees few obvious templates: "Bush and Clinton did theirs from here (the White House), George H.W. Bush went to West Point, gave a foreign policy speech," he told AFP. "They are all totally different."
Obama's trip to Chicago is about more than nostalgia, Keenan indicated.
"The thread that has run though his career from his days as community organizer to the Oval Office is the idea that if you get ordinary people together and get them educated, get them empowered, get them to act on something, that's when good things happen," he said.
"Chicago is not just his hometown, it's where his career started."
And now it is also where Obama's presidential career will effectively end.