Yannis Palaiologos is the op-ed editor for the Kathimerini newspaper in Athens. He is the author of “The 13th Labour of Hercules: Inside the Greek Crisis.”

ATHENS — Sunday’s parliamentary elections amounted to a stinging defeat for both left and right populism in Greece. After a long slog in bailout purgatory, and 4½ years under a populist government of the hard left and the nationalist right, Greeks turned decisively to the establishment center-right New Democracy party, led by Kyriakos Mitsotakis. Now it is up to the new prime minister to deliver the reforms that will permanently consign the forces of extremism to the margins.

Ousted prime minister Alexis Tsipras, leader of the leftist Syriza party, came to power promising to end austerity and rid the country of the endemic corruption of the old political system. Tsipras’s defeat is a testament to his failure on both those fronts — and indicative of the struggles of populists everywhere to turn their simplistic and overblown campaign rhetoric into practical political reality.

Sunday’s returns were also disastrous for the Golden Dawn, a racist party with Nazi roots that became Greece’s third-largest party in 2015, even though its leaders had been arrested for running a criminal organization. (The trial is still ongoing.) This time, the group failed to cross the 3 percent threshold and make it into Parliament.

It was another sign of the resilience of Greek democracy, which was severely tested by the deepest depression ever faced by a developed country in peacetime, in a period of resurgent authoritarianism in Europe and the world. As the various populist myths about the causes and possible solutions to Greece’s crisis have been revealed as delusions and outright lies, the fuel that sustained extremism has been depleted.

Mitsotakis, 51, enters office with an absolute parliamentary majority, the first since Greece applied for its first bailout in 2010. The scion of one of Greece’s most famous political families, this Harvard- and Stanford-educated former banker and management consultant has benefited from being serially underestimated, either for lacking Tsipras’s common touch or for holding free-market views that are out of the mainstream of his own statist party. Greek voters responded well to his low-key approach, his unifying message and his unwillingness to promise the world to them. Exhausted from years of anger and division, from demagogues of the left and the right placing the blame for Greece’s catastrophe everywhere — on immigrants, international bankers, the European Union — but on our own failed political economy, they opted for a return to normality. Syriza’s high percentage, above 31 percent, is another indication of this — Greece seems to be reverting to a strong two-party system after years of fragmentation.

Yet the country’s challenges remain staggering — public debt levels at 181 percent of gross domestic product, a fiscal straitjacket imposed by its European creditors, a rapidly shrinking population, a banking system weighed down by a mountain of bad loans. If the new government goes back to business as usual — appointing party hacks to key posts in the public sector, attempting to manipulate the justice system and intervening in a heavy-handed way in the economy — then Greece’s slide will continue. A stagnating economy and perpetual austerity will be the perfect breeding ground for a revival of populism — perhaps in a more virulent form.

Mitsotakis must keep the party barons in line, be ruthless with symptoms of corruption and fight off accusations of elitism. His opponents will paint him as leading a government for the rich. Not too long ago, another technocratically minded former banker, French President Emmanuel Macron, was elected to office and hailed as an antidote to populism. Today, his approval ratings are sagging, and his high-handed style helped reinvigorate French populist forces.

If Mitsotakis puts a premium on good government and takes advantage of voters’ newfound maturity to push through necessary reforms, the Greek economy can grow in strides. Lower taxes, a streamlined, more efficient bureaucracy and faster court proceedings will create a favorable business climate. Tackling established interests in key sectors, such as energy, will bring in desperately needed investment. A growing economy would in turn attract many of the hundreds of thousands of young, educated Greeks who emigrated during the crisis and have thrived abroad. If enough of them return home, they might constitute a powerful voting bloc in favor of further reform.

If all that happens — and it is a big if — then populism in Greece will be left without a leg to stand on.

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