An untested whizkid has shot to power as President of France in his very first election campaign, crumpling older, hard-bitten veterans in his wake.

Emmanuel Macron‘s astonishing rise from provincial straight-A student to Rothschild banker, to civil servant, to Sunday’s victory as President of the sixth-biggest economy in the world seems like one of the mythic tales of success familiar to all French children, in which a gallant young hero overcomes impossible odds to achieve giant success.

Aged just 39, Macron is France’s youngest leader since the famed French emperor Napoleon Bonaparte, who took power at age 35.

Thousands of people poured in the huge courtyard of the Louvre Museum after polls closed at 8 p.m. on Sunday night, hugging each other and chanting “Macron Président!” as they waved flags. Macron defeated Le Pen by 66.1% to 33.9%, with 99% of votes counted.

From outside the Louvre, Meriem Tertouche, 40, an immigrant from Algeria, said she drove into Paris with her three small children from their home 120 miles away to celebrate Macron’s victory, adding that she had been “horrified by Le Pen and all her talk against immigrants.”

In an address to the nation from inside his office, Macron said he had sensed the “rage, anxiety and doubt” coursing through much of France. “The renewal of public life starts tomorrow,” he said.

And yet, after Macron takes the oath of office inside the ornate Elysée Palace next Monday, the years ahead could hold far more difficult and complicated plot twists than those heroic tales suggest—challenges that will likely make his past five months of campaigning seem simple.

Macron, who was barely known just a year ago, when he was President François Hollande’s Economy Minister, won over many French voters as much for his jolting fresh-faced vigor and his razor-sharp intellect, as for his policies themselves. “He’s our own J.F.K.,” cooed one supporter during a Macron rally in late April, who said she had ditched her support for the traditional conservative Republican candidate in order to back Macron.

But youthful energy will take Macron only so far. And millions, too, voted for Macron not for what he represented, but for who he was not: His far-right rival, National Front leader Marine Le Pen.

Just like that other young leader Napoleon, Macron inherits a country that is bitterly divided and mired in problems that have endured for years. Those include double-digit unemployment—about 24% among young French—serious terrorist threats, Europe’s biggest migrant crisis since the Second World War, marked skepticism over the E.U., and ballooning public debt.

In March, Macron told TIME he aimed to win people over to his ideas—ones that include even tighter E.U. coordination, and a far-reaching economic overhaul. “My point is to convince the French people that a positive project and a progressive view is more adapted to our challenges,” he said.

That will be no small feat, however.

Having ridden to power on a groundswell of voter exasperation, Macron now has to somehow unite France without any political party of his own; he founded his movement, called En Marche! (On the go) just 13 months ago, drafting thousands of young unpaid volunteers on Facebook and sending them out across the country to ask regular French citizens what they wanted from their leaders; people were amazed to be asked the question.

“This was very much like a U.S. movement,” Guillaume Liegey, partner at the Paris political strategy group Liegey Muller Pons, who designed Macron’s door-knocking methods, told TIME last week. “He did what Obama did in 2007. He built a movement outside of the party structure.”

If Macron was Obama-like, Le Pen’s campaign seemed to channel that of Donald Trump, whose victory she hailed as a prelude to her own. Much like Trump, she campaigned on closing the borders, virtually stopping all immigration, and ripping up free-trade agreements, in particular by getting France out of the E.U., and dropping its use of the Euro in favor of a national currency. The choice, as Le Pen put it, was between “patriots” and those who supported what she called Macron’s “savage globalization.”

On Friday, Macron admitted his campaign had evolved over the months “by the anger we found in the country,” he said, during his final interview as candidate, with the French website Mediapart. “There is a very deep fracture,” he said. “We have to reconcile it.”

Macron’s victory has shattered the two-party system of Socialists and conservatives that have endured for 60 years. That system, he told TIME last summer, before he launched En Marche!, was “sclerotic.”

But what comes next is not entirely clear, and Macron has little time to piece together a replacement for the old structure.

Immediately, Macron needs to forge a coalition capable of winning a majority of seats in the French parliament, called the National Assembly, whose elections are in June. Without that, he could find it intensely difficult to ram through his campaign promises, which include cutting 160,000 positions in France’s mammoth public-service sector, cutting corporate taxes from 33% to 25%, and cutting the huge payroll taxes, which economists (like Macron) believe keep companies from hiring more people. Macron’s campaign spokeswoman Laurence Haim told TIME last month they were vetting about 15,000 candidates to run in the June elections.

That is only one problem, however. The other big hurdle ahead is his vanquished rival, National Front leader Le Pen.

In their presidential debate last Wednesday night, Macron laid into Le Pen for making fraudulent promises to fearful French voters, accusing her of sprinkling poudre de Perlimpinpin, or snake oil, among them.

Yet Le Pen’s “France first” message hit home among millions of voters, especially in the hard-hit northern Rust Belt, where she and Macron brawled in the campaign’s final days over the fate of Whirlpool factory in the city of Amiens, where 290 workers are set to lose their jobs next year when production moves to Poland.

Even in defeat, Le Pen could present a menacing political force to Macron if the sluggish economy fails to improve. She repeatedly cast Macron as a rich banker with no concern for the working poor, and as the ultimate embodiment of the elite status quo.

Key Le Pen aides have told TIME in the past few days that they regard their campaign as a huge success, despite her loss, since they have effectively placed the National Front’s anti-immigrant ideas at the center of French political debate. “We have totally changed the whole paysage [landscape] of French politics,” Ludovic de Danne, Le Pen’s foreign affairs advisor, told TIME in an interview last week. As for her prospects in 2022, says de Danne, “she will be in a good position.”

In his final interview as candidate, on Friday for the investigative French website Mediapart, Macron admitted he faced some steep obstacles ahead. “Politics is not a game that you win every time,” he said. For now, at least, Macron has won the biggest contest of all.

Correction: The original article misstated the age of Napoleon Bonaparte when he became Emperor. He was 35, not 40.

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