Mr Yousaf announced his plan to cut ties with the Greens earlier on Thursday, following a bitter row over the SNP's climbdown on climate targets.

And soon after, the Scottish Conservatives announced it would lodge a vote of no confidence in him, claiming the first minister had "failed" in his role and had "focused on the wrong priorities for Scotland".

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Both Labour and the Liberal Democrats agreed to back the motion, with its success hanging on whether Green Party MSPs joined the attack to give SNP critics a majority in Holyrood.

But its co-leader, Patrick Harvie, is now expected to make an announcement at 5.30pm confirming they will join forces to condemn Mr Yousaf's leadership, with Green sources telling Sky News there was serious anger among the ousted party.

If the vote passes, it will still be up to Mr Yousaf to decide on how to respond. However, its puts increasing pressure on his position if he fails to hold the confidence of the majority of the parliament.

However, if a no confidence vote was passed on the government, the SNP government would have to resign and appoint a new first minister within 28 days or call an election.

Speaking to the Press Association, the Green's other co-leader, Lorna Slater, accused the first minister of "caving in to the conservative, right-wing branch" of his party.

"We supported Humza Yousaf to be first minister last year on the basis of a pro-independence majority government, where we would be working together to deliver rent controls, to deliver real change on climate, nature, new protections for tenants," she said.

"Today the first minister decided to tear up that agreement... so we no longer have confidence in a progressive government in Scotland doing the right thing for climate and nature."

The power-sharing deal between the SNP and the Greens was made in 2021, after Nicola Sturgeon's party came in just shy of an outright majority in the Holyrood election of the same year.

Both backers of Scottish independence, the deal between the parties - named after the first minister's official residence in Edinburgh - brought the Greens into government for the first time anywhere in the UK, with both Ms Slater and Mr Harvie given ministerial posts.

But signs the agreement was running into difficulty came after the Scottish government scrapped its commitment to cut emissions by 75% by 2030.

The Greens were also dismayed at the pause of puberty blockers in the wake of the landmark Cass review of gender services for under-18s in England and Wales.

The party had been expected to hold a vote on the future of the agreement, but before they got a chance, Mr Yousaf summoned his cabinet and announced on Thursday that the deal had "served its purpose".

The first minister said he hoped to pursue a "less formal" agreement with his former partners and heralded what he called a "new beginning" for the SNP, saying his decision showed "leadership".

But with the Greens now ready to join those against the SNP, there is a possibility it could instead prompt an end to his premiership.