Austria’s Chancellor Sebastian Kurz faces being removed from office in a no-confidence vote on Monday afternoon.
His previous coalition ally, the far-right Freedom Party (FPÖ), said it would support the motion being brought by the opposition Social Democrats.
The FPÖ had become embroiled in a political scandal caused by a secret video, which ended the coalition.
If Mr Kurz is forced out, a new chancellor would lead a caretaker government ahead of elections.
They are expected in September.
Mr Kurz, head of the conservative Austrian People’s Party, could become the first chancellor in post-war Austrian history to be removed from office in this way.
At 32, he is the world’s youngest state leader.
What will happen in parliament?
There will be two no-confidence votes, one against the government and the other against Mr Kurz individually.
The motions have been submitted by the opposition Social Democrats, with the debate due to begin at 13:00 (11:00 GMT).
But they only have 52 seats in the 183-seat lower chamber.
Unfortunately for Mr Kurz, the FPÖ has signalled it will back the motion, and it has 51 seats.
A majority is all that is needed in the votes.
Mr Kurz’s surprise strong showing in Sunday’s European Union elections – with a projected 35% of the vote – may not be enough to save him.
On Facebook he accused the parties of a “game of revenge” adding: “But at the end of the day the people will decide, namely in September.”
The parties ranged against Mr Kurz appear to believe he should shoulder some of the blame for the fall of the coalition.
The Social Democrats say he should never have allied himself with the FPÖ in the first place. The FPÖ is still smarting from having had Mr Kurz replace all of its ministers with technocrats.
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Mr Kurz meanwhile has promoted himself as a bastion of stability amid the turmoil.
What’s the video scandal about?
It has widely been labelled “Ibiza-gate”, after the Spanish island where the video was recorded.
It was secretly filmed in 2017 just weeks before the election which saw both the FPÖ and Chancellor Kurz’s party perform well.
In the footage, released by German media, Freedom Party leader and vice-chancellor Heinz-Christian Strache can be seen relaxing and drinking for hours at a villa with FPÖ parliament group leader Johann Gudenus, while they meet a woman, purported to be the niece of a Russian oligarch.
Mr Strache appears to propose offering her public contracts if she buys a large stake in the Austrian newspaper Kronen Zeitung – and makes it support the Freedom Party.
He is heard suggesting that a number of journalists would have to be “pushed” from the newspaper, and that he wants to “build a media landscape like [Viktor] Orban” – referring to Hungary’s nationalist leader.
Mr Strache stood down hours after the video emerged.
President Alexander Van der Bellen then fired FPÖ Interior Minister Herbert Kickl at the request of Mr Kurz.
The move prompted the FPÖ’s other ministers to resign in solidarity.