Donald Trump's jaw-dropping White House win is a slap in the face for Barack Obama, elected eight years ago as the country's first black president on the promise of a nation united.

At the political level, Hillary Clinton's defeat is certainly a setback for Obama, who campaigned hard for his former secretary of state, traveling across the country and employing the charisma and charm that she sorely lacks.

But, aside from being the loss of a typical battle between the two major American political parties, the 70-year-old real estate tycoon's success is also a stinging personal blow for Obama.

It certainly appears that as if this ever calm, cerebral and optimistic president failed to understand a large slice of the American electorate and appreciate their reflexes,    Indeed, it would seem Obama has failed to take the pulse of this other America, a world of working class whites who felt they have been left in the lurch amid rapid-fire change from globalization and an increasingly multicultural society.

Over the short term, Obama, whose approval ratings remain high as he prepares to leave office in January, might well ask what will even be left of his legacy after a Trump administration.

Trump has promised to scrap or overhaul many of Obama's signature initiatives, such as the health-care plan that bears his name, the battle against climate change and the Paris accord of 2015, and the proposed Trans-Pacific Partnership trade deal.

Obama has stated adamantly that Trump, criticized as a loose gun on everything from foreign policy to his treatment of women, is a danger to democracy.