US President Barack Obama is set to meet his successor Donald Trump in the Oval Office for talks aimed at ensuring a smooth transition of power.
Trump will become the 45th US president after securing a surprise victory over Hillary Clinton.
Obama mounted a fierce campaign to prevent Trump from winning the White House, branding him "unfit" for office.
But the president has now urged all Americans to accept the result of Tuesday's election.
"We are now all rooting for his success in uniting and leading the country," Barack Obama said of Trump.
Despite Obama's calls for unity and Clinton telling supporters Trump must be given a "chance to lead," his victory has sparked protests in several US states.
Hundreds of Anti-Trump demonstrators in New York staged a march on Trump Tower in Manhattan on Wednesday evening, waving placards declaring "Not my president" and other slogans.
Police earlier erected concrete barriers and other security measures outside the 5th Avenue skyscraper, which is likely to be Trump's headquarters during the transition to power.
There were also reports of protesters blocking the entrance to Trump Tower in Chicago on Wednesday evening, chanting: "No Trump, No KKK, No Fascists USA" and "Not my president!"
In Oakland, California, and Portland, Oregon, protesters have reportedly burned American flags.
In his victory speech in the early hours of Wednesday, Trump vowed to "bind the wounds of division", after the acrimonious election contest, and to be "president for all Americans".
White House spokesman Josh Earnest has insisted Obama will be sincere about ensuring a smooth handover when he meets Trump, although he added: "I'm not saying it's going to be an easy meeting."
The president-elect will be accompanied to the White House on Thursday morning by his wife, Melania, who will have a meeting with First Lady Michelle Obama in the White House residence.
Obama, who congratulated his successor in a phone call in the early hours of Wednesday, said it was "no secret" that he and Trump had pretty significant differences.
But he added that "we all want what's best for this country" and he was "heartened" by what he heard in Trump's remarks the night before.
Trump's transition team for the 10-week period until inauguration will be led by Chris Christie, the governor of New Jersey.
The president-elect, who has never held elected office, has said his immediate priorities will be restoring the country's infrastructure and doubling its economic growth.
Republican National Committee Chairman Reince Priebus said: "Donald Trump is taking this very seriously," adding that the business mogul's deal-making ability would enable him to quickly "make things happen for the American people".
As president-elect, Trump is entitled to get the same daily intelligence briefing as President Obama, which includes information on covert US operations and other data gathered by America's 17 intelligence agencies.
Trump's team is understood to be focused on quickly filling key national security posts.
But it is not yet clear who will sit in his cabinet or fill senior posts in his administration, such as chief of staff.
There are expected to be roles for Christie, former House Speaker Newt Gingrich and former New York Mayor Rudy Giuliani, another of Trump's closest advisors, who is being linked with the role of attorney general or national security adviser.
After losses overnight as Trump's surprise victory became clear, financial markets rebounded as a feared meltdown failed to materialise.