The Socialists, led by Chancellor Christian Kern, 51, finished third with 26.7 percent of the vote, preliminary results showed.

The most likely coalition partner appeared to be the nationalist, populist Freedom Party, which initial results showed winning 27.1 percent of the vote. The party complained during the election campaign that Mr. Kurz had stolen its playbook, seizing on issues like limits to immigration and the threat posed to Austrian identity by Islam.

The Freedom Party, led by Heinz-Christian Strache, 48, was believed to be eager to join the government. The party had hoped for a stronger showing months after it narrowly lost the presidency to Mr. van Der Bellen, a former leader of the Greens.

Despite participating in neo-Nazi activities as a youth, Mr. Strache has tried to cast his party in a more centrist light — unlike previous leaders who were known for remarks sympathetic to the Nazis — while remaining sharply critical of Islam. He has insisted that the party would not call into question Austria’s European Union membership if it entered the government.

“We say yes to Europe, but we are critical,” Mr. Strache said on Sunday.

The Austrian result is the latest indication of Europe’s shift to the right, after the far-right Alternative for Germany party won more than 90 seats in the German Parliament last month, making it the third-largest bloc in the legislature.

The strong showing by right-leaning populist parties in the German-speaking world appeared to give new momentum to a surge of populism in Europe, after defeats of nationalists in the Netherlands and France.