WASHINGTON, United States (AFP) — Barack Obama and Donald Trump put acerbic rows and profound differences aside in a 90-minute transition meeting at the White House yesterday, hoping to quell fears about the health of the world’s pre-eminent democracy.

The outgoing president and his successor met one-on-one and sat in high-backed chairs before the Oval Office fireplace, for what Obama characterised as an “excellent conversation”.

The meeting, which came less than 36 hours after Trump’s shock election victory over Democrat Hillary Clinton, had the potential to be awkward. The two had traded barbs during the heated battle for the White House.

Trump — who previously called Obama the “most ignorant president in our history” — said it was a “great honour” meeting with the US leader, adding that he looked forward to receiving the president’s counsel.

Obama — who previously said Trump was a whiner and “uniquely unqualified” to be commander-in-chief — vowed his support.

He told Trump that his Administration would “do everything we can to help you succeed, because if you succeed, then the country succeeds”.

The two men ended the improbable and historic White House encounter with a handshake and refused to take questions.

“Here’s a good rule. Don’t answer questions when they just start yelling,” Obama told Trump, referring to the press.

White House officials said that the two men had discussed a range of issues, including Obama’s meetings with leaders from Germany, Greece and across the Asia-Pacific during foreign travel next week.

On that trip, Obama is likely to be inundated with panicked questions about America’s role in world affairs.

Anger over the Republican property mogul’s upset election win over Clinton spilled out onto the streets of US cities late Wednesday as chanting protesters lit bonfires and snarled traffic.

But in the days after Trump’s shock election win, which virtually no poll had predicted, both sides spoke of healing the deep divisions sown in a bruising two-year campaign.

Trump’s vanquished Democratic rival Clinton, holding back the bitter disappointment of not becoming America’s first female president, urged the country to give Trump a chance.

“We owe him an open mind and the chance to lead,” she said Wednesday in a concession speech.

Obama, addressing disconsolate staff in the White House Rose Garden, played down Trump’s win as part of the messy “zig-zag” movement of a democracy.

“Sometimes you lose an argument,” he said, adding that all Americans should now be “rooting” for Trump’s success.

In the battle for the soul of America, those who helped elect its first black president now appear to be in retreat and pondering whether his eight years in power have come to naught.

Both Obama and Clinton issued a faint — but clear —warning that Trump must respect institutions and the rule of law if a modicum of goodwill is to hold.

That “likely” observance of rule of law may not suffice for Washington’s partners and allies, who see an entire global political order built around US leadership cast into doubt.

German Chancellor Angela Merkel was quick to underscore the importance of shared democratic values.

“On the basis of these values, I offer close co-operation to the future president of the United States of America,” she said.

Europe, already beset by financial and social crises and internal divisions, now faces existential questions about its own security. Trump has questioned the US-led NATO’s key collective defence guarantee.

The leaders of America’s neighbours, Canada and Mexico, quickly made clear their willingness to work with the new president.

President Enrique Pena Nieto of Mexico, a prime target of Trump’s anti-immigration campaign rhetoric, reached out to congratulate the incoming leader and announced they would soon meet.

The Republican Party leadership, too, embraced their newfound champion.

House Speaker Paul Ryan, who had distanced himself from Trump in the final month of the campaign, pledged to “hit the ground running” and work with him on conservative legislation.

The two, along with Vice-President-elect Mike Pence, met on Capitol Hill for lunch after Trump’s talks with Obama.

On Wednesday, Trump huddled at Trump Tower in New York with a group of advisers, planning a transition strategy to take over stewardship of the world’s largest economy.

Team Trump unveiled a transition website —

www.greatagain.gov — that highlights the colossal human resources challenge facing the incoming administration under the headline ‘Help wanted: 4,000 presidential appointees’.

During a bitter campaign that tugged at America’s democratic fabric, the tycoon pledged to deport illegal immigrants, ban Muslims from the country and tear up free-trade deals.

Those campaign messages were embraced by a large section of America, grown increasingly disgruntled by the scope of social and economic change under Obama.

But they were passionately rejected by Clinton supporters.

Thousands of protesters — in New York, Los Angeles, Boston, Chicago, Philadelphia, Portland and other cities and school campuses – rallied Wednesday to express continued opposition to the incoming leader they accuse of racism, sexism and xenophobia.

In Los Angeles, a giant Trump head was burned in effigy.