"Make no mistake: the world's biggest power is now in the hand of the extreme right," says left-leaning Libération in an editorial penned after the Republican's win over Democrat Hillary Clinton was announced.
Most of Trump's voters were "white men, from a middle class in complete disarray, frightened by loss of social status, poverty, immigration, terrorism, the federal state and above all the fear of losing their majority status", it believes.
Right-wing Le Figaro also sees a "suffering working and middle class, worried about everything ... the decline in prosperity, opening of borders, globalisation and multiculturalism, massive immigration".
"A community, often white, ghettoised in its turn" is "locked in an obsession of loss of social status and marginalisation", it comments.
"The country that elected Barack Obama in 2008 and 2012 ... has just honoured a property speculator several times bankrupted who declares his pride in his 'good' European genes," centrist Le Monde notes.
"This Trump is uncontrollable," Libération judges. "Our unstable world did not need such a loose cannon."
Xenophobia and the far right are on the rise in Europe thanks to "ultraliberalism without limits", it says. "But this time it is in the very temple of the unregulated financial economy that the cocktail has become explosive."
Le Figaro warns that the result should "sober" Europe's democratic elites, especially after the UK's Brexit vote and the "rise of anti-system parties from one end to another of the Old Continent".
"American anger is just the older cousin of European revolts," it says. "It will not dissolve like a gunpowder-filled sky on the night after a battle."
This anger focuses on two main themes, immigration and income inequality, Le Monde points out. "Trump predicted a Brexit to the power of three. He was right. That's also a way of saying that Europe is in no way protected from the earthquake that has just shaken Washington."
Le Pen win possible
That means danger signals so far as next year's presidential election in France, according to Libération and Le Monde.
"In the world after this election anything is possible," the latter says, "even what we have trouble facing up to: an extremist party taking power."
"This election is yet another warning to those who think that [National Front leader] Marine Le Pen cannot come to power in France in 2017. And yet another proof that no step is too high for liars and hucksters. Especially when the leaders of 'republican' parties give them a leg up by validating indentitarian and racist ideas."
Economists predict short-term boom, long-term problems
Le Figaro interviews four economists about Trump's economic policies.
They say a short-term boom is possible, thanks to his promise to spend more on infrastructure and lower taxes.
But it may not last and the ratio of debt to GDP will explode, they warn.
And, if he carries out his threat to raise trade barriers, countries will retaliate and exporters to the US, like Germany, will suffer.
Lieven Jacobs, of Quilvest Asset Management, believes that Trump's fellow Republicans may block some of his proposals, notably the threat to deport 11 million undocumented immigrants, which "could have a negative effect on the labour market".
"Congress is very pragmatic, anything that doesn't serve the country's interests doesn't get through," he comments.
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