Tight race likely to upset Austrian power

Although the role is mainly symbolic, the ballot is a key indicator of the parties' standing ahead of the general election in 2018.

"Like elsewhere in Europe, we are witnessing the downfall of the traditional parties," political expert Peter Hajek told AFP.

"They have failed to modernise over the past decade and attract new voters."

The so-called "great coalition" between the Social Democrats (SPÖ) and the conservative People's party (ÖVP) has dominated Austrian politics for the best part of the last 70 years.

But polls suggest their candidates trail far behind in Sunday's race.

Tight race

Instead, voters are set to pick one of three wild cards: Norbert Hofer of the far-right Freedom Party (FPÖ); ex-Green party leader Alexander van der Bellen; or Irmgard Griss, the former president of the Supreme Court and the only woman in the contest.

In a tight race, van der Bellen is projected to get up to 26 percent, Hofer 24 percent and Griss around 21 percent.

A run-off vote will take place on May 22 if no one manages to obtain an absolute majority.

The chances are slim that it will include the SPÖ's Rudolf Hundstorfer or the ÖVP's Andreas Kohl, stuck on 15 and 11 percent respectively.

The only person faring worse in the six-person contest is the eccentric Viennese businessman Richard Lugner who has three percent.

The president has usually come from one of the two main parties, or had the backing of one of them in the case of independent candidates.

But cracks have begun to show in the alliance, which has come under pressure over the migrant crisis and rising unemployment -- factors that have sparked a surge in popularity for the FPOe.

Parties punished

The party, led by Heinz-Christian Strache consistently scores more than 30 percent in voter surveys and could come first in the 2018 ballot.

"In the past, the presidential election focused on personalities but this year political issues have also come into play. Hundstorfer and Kohl will have to pay for their parties' failings," said Karin Cvrtila of the OGM polling institute.

Heads could roll in the current government if neither candidate makes it into the run-off, she added.

Whoever ends up victorious, the three frontrunners have already declared they want to be "more active" in government than the incumbent Social Democrat Heinz Fischer.

The president is in fact a powerful person: in addition to being the army chief, he or she can dismiss the government and reject a chancellor candidate.

"The role is like that of a sleeping giant who has a lot more authority than people are aware of," legal expert Manfried Welan told AFP.   

"Conventions will change as we're entering a multi-party landscape."

Hofer -- described as the "friendly face of the FPOe" who likes to wear his Glock gun out in public -- has threatened to fire the government if it did not follow a tougher stance on migrants.

Van der Bellen, a soft-spoken independent with Green backing, said he would refuse to swear in Strache as chancellor, prompting Hofer to call him a "fascist green dictator".

Meanwhile Griss, another independent candidate, announced she would consider redefining the army's role.

However, experts like Hajek warn that while Austria's 6.4 million eligible voters seek change, "they don't want a complete game-changer".