For the second time in less than a week, a right-leaning populist politician has confounded the experts and is poised to win a major election in a landslide. This time, the vote was in the Netherlands and the politician is Geert Wilders of the Party for Freedom.

Mr. Wilders, who for two decades has been one of the Netherlands’ most outspoken critics of unfettered immigration from the Islamic world, is leading exit polls in a result that is sure to send shockwaves through Europe.

The results of Wednesday’s election puts him in line to lead talks to form a new ruling coalition and possibly become the country’s prime minister for the first time. The exit poll published by the national broadcaster NOS said Mr. Wilders’ party won 35 seats in the 150-seat lower house of parliament, more than double the 17 he won at the last election.

The closest party to Mr. Wilders’ Party for Freedom was an alliance of the center-left Labor Party and Green Left, which was forecast to win 26 seats.

In a Europe increasingly rocked by open antisemitism since the war in Israel began October 7, Mr. Wilders stands out as one of Israel’s staunchest supporters. As a young man, he lived for two years in the Jordan Valley and has called Israel “a place where I feel home.”

Following the attacks by Hamas terrorists, he called on Europeans to “vigorously support” Israel and described the conflict as a “war between freedom and barbarity.” He has also advocated for moving the Netherlands’ embassy in Israel to Jerusalem from Tel Aviv.

Mr. Wilders’ election program includes calls for a referendum on the Netherlands leaving the European Union, a total halt to accepting asylum-seekers and migrant pushbacks at the Dutch borders. It also advocates the “de-Islamization” of the Netherlands, although he has been milder about Islam during this election campaign than in the past.

The lawmaker, though, would have to form a coalition government before he could take the reins of power. That is likely to be tough as mainstream parties are reluctant to join forces with him and his party. The size of his victory could strengthen his hand in any negotiations.

The exit poll was published as voting ended in the general election. It can have a margin of error of up to three seats, but generally is accurate within one or two seats, Ipsos said.

The election was called after the fourth and final coalition of outgoing Prime Minister Mark Rutte resigned in July after failing to agree to measures to rein in migration.

Mr. Rutte was replaced by Dilan Yeşilgöz-Zegerius, a former refugee from Turkey who could have become the country’s first female prime minister had her party won the most votes. Instead, it was forecast to lose 11 seats to end up with 23.

The election had been called a neck-and-neck race, but in the end Mr. Wilders handily beat all opponents. The result is the latest in a series of elections that is altering the European political landscape. From Slovakia to Spain to Germany, populist and hard-right parties triumphed in some EU member nations and faltered in others.

Mr. Wilders’ ascent mirrors that of the Argentine president-elect, Javier Milei, who last weekend surprised most election analysts there by handily defeating the socialist Sergio Massa, an incumbent tied to the Peronist party that has reigned over Argentine politics for decades.

Mr. Melei, a libertarian firebrand who calls himself an anarcho-capitalist, captured the imagination of Argentina’s youth with promises to make the American dollar his nation’s currency and slash government spending to curb triple-digit inflation. In an interview published late Tuesday, the president elect, who takes office December 10, promised a “shock therapy” to cure the country’s various maladies.

“There’s no money. There’s no money,” Mr. Milei told the Argentine news outlet Neura Media. “If we don’t make a fiscal adjustment, we’re headed for hyperinflation. We’ll have hyperinflation and we are going to have 95 percent poverty and 70 percent or 80 percent homeless.”