VIENNA (AP) — The outcome is unclear as Austrians vote for their next president. But one thing is nearly certain — for the first time the winner is unlikely to be a candidate supported by either of the two mainstream parties that have dominated politics since World War II.

Voting began Sunday with the latest polls showing support of 11-15 percent for contenders backed by the Social Democrats and the centrist People's Party, which have governed alone or together for decades.

That's well short of 21-24 percent backing predicted for Norbert Hofer of the anti-immigrant Freedom Party and Alexander Van der Bellen and Irgmard Griss, who are running as independents. And it suggests political uncertainty lies ahead in a country where government stability has been the norm.

No candidate is expected to get a majority Sunday, making a runoff likely on May 22.

With Social Democrat Rudolf Hundstorfer and People's Party candidate Andreas Khol long shots, that second round will likely see either Van der Bellen or Griss, both liberals, face Hofer, whose law-and-order stance is meant to capitalize on the Freedom Party's popularity.

Driven by concerns over Europe's migrant crisis, the Freedom Party has surged to 32 percent of voter support compared with just over 20 percent for each of the governing parties.

But voters were unhappy with the Social Democrats and the People's Party even before the migrant crisis last year forced their coalition government to swing from open borders to tough asylum restrictions. Their bickering over key issues — most recently tax, pension and education reform — has fed perceptions of political stagnation.

That could translate into a win for Hofer and trouble for the traditional parties. Instead of focusing on the office's symbolic functions like past presidents, he has threatened to dismiss the government coalition and call a new national election — something no president has done since the office was newly defined after World War II.

His tough stance means that whoever opposes Hofer is expected to be able to line up a sizable number of votes from Austrians who backed the socialists or centrists in round one but are opposed to the Freedom Party.

That has led some of those casting ballots Sunday to suggest that they were less interested in backing one candidate than keeping another out of office.

"There's a strong trend towards voting for the FPO," said Stefanie Wagner, using the Austrian acronym for the Freedom Party. "That's exactly what I want to prevent with my vote.

"But I think it's going to be a close shave."

Associated Press video journalist Philipp Jenne contributed.