“The European Union will die!” France’s far-right presidential contender Marine Le Pen said during a campaign rally on March 26 in Lille. (Sylvain Lefevre/Getty Images)

As European leaders assembled in Rome to herald the 60th anniversary of an embattled European Union, Marine Le Pen — fresh off the plane from a somewhat mysterious visit to Moscow — took to the podium this week in this middle-class French city.

After an entrance fit for a queen or a Kardashian, the presidential contender and leader of France’s far-right National Front delivered one simple message to the thousands of supporters who crammed into stadium seats to catch a glimpse of her, waving French flags and screaming her name.

“The European Union will die!” Le Pen proclaimed, to a round of raucous applause. “The time has come to defeat the globalists.”

In late April and early May, voters in France’s highly contentious presidential election will decide the future of a country that has struggled with high unemployment, an unprecedented national security threat and a steady stream of largely unwanted migrants. But they will also decide the immediate future of the E.U., a troubled institution that will be saved or destroyed by the will of the same nation that spearheaded its creation. The French election has become the decisive referendum on the dream of a unified Europe, six decades later.

(Bastien Inzaurralde/The Washington Post)

“That’ll be the real significance of the French elections: the survival or the demise of the EU,” wrote Gérard Araud, France’s ambassador to the United States, responding to Le Pen’s Lille remarks on Twitter. The sentiment is shared in Paris and Brussels, throughout France and across Europe: The fate of the bloc lies with the French.

In recent years the European project — which once knew only expansion — has suffered devastating blows.

The austerity measures enacted in Europe’s sovereign debt crisis grossly undermined the E.U.’s reputation in many southern member states, the historic migration crisis invigorated a once-dormant network of right-wing populist parties, and the Brexit vote rendered the distant prospect of dissolution a pressing reality.

A French departure from the bloc is a possibility, and that, leaders and analysts say, would be instantly fatal in ways that none of Europe’s other recent traumas have been.

There are five candidates for the French presidency: Two advocate abandoning the E.U., two are harshly critical of the enterprise, and one argues for it — although with the explicit acknowledgment that the institution needs more democratic oversight and engagement. According to current polls, the race will boil down to a contest between Le Pen and Emmanuel Macron, the independent, pro-Europe candidate.

Macron, a 39-year-old former investment banker, cuts a familiar figure in Europe’s transnational landscape. He has campaigned in Berlin — in English — and speaks about Europe in terms dramatically different from Le Pen’s.

“Europe, it’s us,” he said in a campaign speech this year, also in Lille. “We wanted it. And we need Europe because Europe makes us bigger, because Europe makes us stronger.”

(Bastien Inzaurralde/The Washington Post)

After an hour-long audience in March with German Chancellor Angela Merkel — who has refused to meet with Le Pen — Macron, a frequent target of Russian media attacks, told reporters that there were “many areas of agreement” between them. For many French voters, the choice between Le Pen and Macron has thus become a stark line in the sand: France or Europe, “us” or “them.”

The E.U. was originally a French vision: Robert Schuman, a former French prime minister, first advocated the integration of Western European heavy industry after World War II, and Jean Monnet, a French economist, saw that integration come to fruition as the inaugural president of the European Coal and Steel Community in the 1950s, an antecedent of the present-day E.U. As the bloc of nations evolved, it grew around a Franco-German core that has run Europe ever since: French leadership managing German economic might. Excising France from Europe’s center would be a bit like removing half a heart — the rest of the organism probably would not survive for long.

Without France, the E.U. would be left without nuclear weapons. It would be shorn of a permanent seat on the U.N. Security Council. The E.U. would also be deprived of one of its biggest economies, one that has long provided a dovish counterweight to German fiscal hawks with their tough approach to debt and balanced budgets. And Euroskeptics in Italy, Finland and elsewhere probably would quickly move to try to dismantle Europe’s remains.

What would be left would be a trading bloc dominated by Germany and deprived of other heavyweights — precisely the scenario that postwar European leaders wanted to avoid.

“It would be an accomplishment of what the Germans tried with two wars, unsuccessfully, without any unit of blame to the Germans,” said Stefano Stefanini, a former senior fellow at the Atlantic Council. “Should Le Pen win against all predictions, it would be game over for the European Union.”

In fact, French voters have rejected Europe once — in a 2005 referendum on whether to adopt the European constitution. Fifty-five percent of voters said no. Whether they will do the same in the 2017 presidential election remains an open question.

The anti-European sentiment in France closely mirrors that of the Brexit and Donald Trump phenomena in Britain and the United States, said Vivien Schmidt, an expert in European integration at Boston University.

“It’s the same discourse of globalization gone too far, of outrage over high unemployment — and especially youth unemployment,” she said. The general unemployment rate in France has hovered around 10 percent for years, and the youth unemployment rate is about 26 percent.

“But it’s also sociocultural,” Schmidt said. “People really feel a loss of control, political and otherwise. Le Pen gives people a nostalgia for a vanished past, a past most people don’t even remember.”

In advance of the Brexit vote, polls indicated that Euroskepticism was even higher in France than it was in Britain. But after the uncertainty of Britain’s future outside the E.U. — and, in the United States, the turmoil that followed the election of Trump — more recent analyses suggest that French voters are unwilling to give up on Europe.

According to the results of a survey published jointly by the CSA Institute and La Croix newspaper last weekend, 66 percent of French voters declared an enduring attachment to the E.U. And even higher numbers — 72 percent, according to a recent Ifop poll — support keeping the euro currency, against a campaign proposal of Le Pen’s to return France to the franc.

Compared with those in Britain and the United States, savings rates in France remain significantly high, and the euro has consequently maintained a relatively high degree of popularity because it has protected against the inflation and frequent devaluations that led the French franc to plummet between 1960 and 1999, when France adopted the euro.

There is also the more oblique issue of identity: Are “French” and “European” somehow mutually exclusive categories, as the National Front has suggested? Or are they complementary, two sides of the same coin?

“It’s true that the French are less European than ever, and there is the sense that Europe is less French than ever,” Pierre Moscovici, a French politician serving as the European commissioner for economic and financial affairs, said in an interview.

“But the French are instinctively, natively, ontologically European. They really don’t have the desire to turn the page, to leave,” he said. “A ‘Frexit,’ that’s a fantasy.”

But leaving the E.U. remains the desired outcome for many French voters, such as Laetitia Bekaert, 45, and her husband, Christophe Bekaert, 46, who braved the crowds to hear Le Pen speak Sunday in Lille.

They voted no to Europe in 2005, they said, and are eager to do so again.

“We can’t continue like this,” said Laetitia Bekaert, a homemaker. “We work so hard, and we give so much to the E.U., which then gives to the arms of millions — but no one here. It’s Europe that decides the price of produce.”

Christophe Bekaert, who said he commutes across the border to work for a British firm in nearby Brussels, agreed. “The law of each country is what’s most important to preserve,” he said.

“France welcomes everyone,” Laetitia said, “but we the French count above all. For me, it’s Marine who is going to save France.”

Birnbaum reported from Brussels.

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