The Social Democrats (SPOe) and the centre-right People's Party (OeVP) have dominated Austrian politics since 1945 and form the unloved current government of Chancellor Werner Faymann.
The president, who ensconced in the Habsburg dynasty's former palace in central Vienna has a largely but not entirely ceremonial role, has usually come from these two parties or had their backing as independents.
But surveys today suggest that neither the SPOe's Rudolf Hundstorfer, 64, nor the OeVP's Andreas Khol, 74, will even make it into a run-off on May 22.
In a tight race, van der Bellen is projected to get around 26 per cent, Hofer 24 percent and Griss 21 per cent, well ahead of Hundstorfer and Khol on 15 and 11 per cent respectively.
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The only candidate expected to fare worse is Richard Lugner, an 83-year-old construction magnate and socialite married to a former Playboy model 57 years his junior.
Support for the two main parties has been sliding for years and in the last general election in 2013 they only just garnered enough support to re-form their "grand coalition".
Leading opinion polls ahead of 2018 general elections with more than 30 per cent is the far-right FPOe, boosted by Europe's migrant crisis despite a firmer line in recent months from Faymann's government.
Austria also no longer has the lowest unemployment rate in the European Union and Faymann's coalition, in power since 2008, has bickered over structural reforms.
The FPOe -- which under the late, SS-admiring Joerg Haider sent shockwaves around Europe after entering government in 2000 -- came second in state elections in Vienna and in Upper Austria last year.
Heads could roll in the current government if neither candidate makes it into the run-off, she added.