(CNN) Minutes into his acceptance speech, Emmanuel Macron acknowledged the "anger, anxiety and doubt" among people who voted for his rival Marine Le Pen. By addressing her supporters so directly and taking their concerns so seriously, the new French president demonstrated that he knows his historic triumph has not crushed populism -- it has merely kept it at bay.

In March, a liberal beat a right-wing populist in the Netherlands . After Macron's victory, Germany's foreign minister, Sigmar Gabriel, tweeted that France "is and will remain in the middle and in the heart of Europe," underlining the two-nation, pro-EU alliance that has been under threat from Brexit and Le Pen.

Denis MacShane, former UK minister for Europe and author of a biography of François Mitterrand, France's longest-serving President, described Macron's win as "the biggest victory for Europe in two decades" that showed "France is willing to resist the waves of populist nationalist extremism of the right and the Podemos-Chavista left, represented by Jean-Luc Mélenchon".

"It is a big win for Angela Merkel and for others seeking to reform and re-dynamise the European Union on the basis of pro-market, pro-entrepeneur and labour reforms. Macron will face many problems, but they are the problems of government and of power," he added.

Yet Le Pen's performance shows that populism remains a potent electoral force.

Her 34% share of the vote is almost double that won by her father Jean Marie Le Pen in 2002. The long-term progress of the Front National shows a steady upwards trajectory, and the party believes it can win up to 40 seats in parliamentary elections next month. Macron's victory has not eliminated at a stroke all the issues that Le Pen was able to convert into votes: immigration, terrorism, unemployment and identity.

Professor Matthew Goodwin, a senior fellow at Chatham House, said: "Despite Macron's triumphant victory, the fact that one in three voters backed Marine Le Pen should remind us all of the lingering appeal of populism.

"It appears unlikely over the longer term that an economic liberal such as Macron will satisfy the left behind workers who have been voting for the Le Pen family since the 1990s. There is likely to remain a sizeable reservoir of support for Le Pen going forward."

Populism, a fluid term

Le Pen -- whose politics are widely seen as racist and fascist -- was endorsed by the pro-Brexit UK Independent Party in Britain and its former leader Nigel Farage.

Yet Dominic Cummings, the campaign director of Vote Leave, the official campaign of the populist pro-Brexit cause in last year's EU referendum, made clear Sunday night that his organization wanted Macron to beat Le Pen, tweeting that "semi/proto-fascist parties with history of Holocaust denial winning elections is v bad for humanity"

In Britain, Theresa May has taken up the populist cause of a hard Brexit, but unlike Le Pen and Trump in the US, she does not pursue a protectionist agenda on trade and globalization.

Nevertheless, Le Pen's brand of populism has entered the mainstream. If she had won the presidency, it would have registered as a global political earthquake, but when she reached the second round of voting last month, few were surprised.

Brian Klaas, a fellow at the London School of Economics and an ex-US campaign adviser, said: "Macron's victory is a crushing defeat for the momentum of extremist populism in Europe.

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"However, Le Pen's showing is comparatively strong and signals the mainstreaming of previously fringe views. This is happening everywhere. In the US, for example, alt-right commentary used to occupy a dark corner of the internet. Now some of its architects are in the Oval Office.

"That's the double-edged sword of last night's defeat of xenophobic populism. It sliced through the momentum forged by Brexit and Trump's victory. Centrist pragmatism won. But by getting more than a third of the vote tonight, Le Pen ensured that nobody can really treat her movement as a 'fringe' political movement."

No one knows this more than the new French president himself, who in his victory speech at the Louvre said of Le Pen's supporters he would do "everything in the next five years so that they have no more reason to vote for extremes".