Kurz is well short of a majority and will probably need a coalition partner to govern. Having pledged to move away from often unworkable coalitions with the centre-left, like the one currently in power, an alliance with the FPO is likely.

Austria was a gateway into Germany for more than a million people fleeing war and poverty in the Middle East and elsewhere in 2015. It made the neutral country fertile ground for parties opposed to the influx.

That propelled Kurz into first place ahead of his current coalition partners, Chancellor Christian Kern’s Social Democrats. The FPO and Social Democrats were in a close race for second that will be settled by a record number of postal ballots that were being counted on Monday.

Kurz champions tough enforcement of the EU’s borders and helped broker border restrictions through the Balkans that largely shut what was then the main migrant route into Europe. He has, however, kept his coalition options open.

“Neither a coalition with the FPO nor one with the SPO has been agreed,” Kurz told broadcaster ORF soon after projections showed his party had won Sunday’s election.

But the likelihood of the FPO entering government with Kurz’s conservatives for the first time since 2000 concerned politicians across Europe.

At that time, a horrified European Union slapped short-lived sanctions on Austria for letting the FPO share power. It was then led by the late Joerg Haider, who gained infamy for praising the employment policies of Nazi leader Adolf Hitler, who was born in Austria.

Austria’s shift to the right came after German voters last month punished Chancellor Angela Merkel’s open-door policy for migrants, pushing her conservative bloc to its worst showing since 1949 and putting the far-right AfD party in parliament.

Merkel said the strong FPO showing was a “big challenge” for other parties and she hoped for close cooperation with Kurz at a European level.

Alexander Lambsdorff, a senior member of Germany’s pro-business Free Democrats that are a possible coalition partner for Merkel, called the Austrian election results “a wake-up call for refugee policy that we finally have to organise together”.

“An orderly refugee policy is what people want, in Austria, in Germany, in other European countries.”

Hungarian Foreign Minister Peter Szijjarto congratulated Kurz for his win, welcoming his stance on migration as close to that of Budapest. He said he expected anti-immigration eastern EU states Hungary, Poland, Slovakia and the Czech Republic to work more closely with Austria now.

Kurz is on track to become one of the world’s youngest leaders after securing around 32 per cent. His hard line resonated with many voters who felt Austria was overrun in the migration crisis – it took in roughly 1 per cent of its population in asylum seekers in 2015.

Under current leader Heinz-Christian Strache, the FPO has become a more mainstream party and sought to rid its ranks of anti-Semitism, focusing instead on fighting political Islam.

But the FPO has had to throw out party officials on a regular basis in Nazi-related scandals.

The biggest opposition party in parliament serves in two provincial and several local governments. It has dropped calls to consider leaving the EU or the euro currency.

Still, World Jewish Congress President Ronald Lauder, who was the US ambassador to Austria from 1986 to 1987, called for the Freedom Party to be kept out of national government.

“It is sad and distressing that such a platform should receive more than a quarter of the vote,” Lauder said in a statement.

Any coalition between two of the top three parties is possible since the SPO has lifted a self-imposed ban on coalitions with the FPO. But if the Social Democrats come third it is unlikely to form an alliance with the FPO that would make Strache chancellor.

Kern’s Social Democrats appear split on how to proceed after years of bickering with their coalition partner the People’s Party left their alliance in deadlock and prompted Kurz to force Sunday’s snap election.