Humza Yousaf and SNP in crisis: 'Humza the Brief'? The First Minister teeters on the brink of political disaster

His political future now rests in the hands of a single MSP, Ash Regan, who he dismissed as "no great loss" when she defected to Alex Salmond’s Alba Party last year. As the chaos unfolded on Thursday afternoon, Ms Regan, who stood against the First Minister in last year’s leadership contest, was spotted outside Holyrood’s bar with a glass of fizz.

Politics, I’m sure she would agree, is a funny old business.

Mr Yousaf will face a vote of no confidence in Holyrood next week, tabled by the Tories and supported by Labour, the Liberal Democrats and the furious Greens. Following the collapse of the Bute House Agreement, the parliamentary arithmetic means the support of SNP MSPs alone won’t save him. He needs Ms Regan, too.

At a press conference in Holyrood’s garden lobby, the Greens denied they were motivated by revenge.

"That would be an unworthy thought,” said Patrick Harvie, the party’s co-leader. “This is about how we achieve the greatest political change for Scotland. Humza Yousaf decided to abandon the vehicle that was delivering that progressive change for Scotland. I think that’s a profound mistake on his part.”

Ms Regan said she had written to the First Minister “about independence, how he's going to defend women's rights, and how he's going to bring competence back to government”. Her vote next week will depend on how Mr Yousaf responds.

“If I were Humza Yousaf, I’d get drafting a very favourable answer, otherwise he’s going to be known as Humza the Brief,” Mr Salmond told Times Radio. The former first minister, cast into the shadows under Nicola Sturgeon, now holds all the cards. And he has been playing this game for a long, long time.

Earlier, Mr Yousaf had been keen to portray his decision as an act of leadership. Speaking at a press conference at Bute House, his official residence in Edinburgh, he said the co-operation agreement had served its purpose, and the SNP would now govern as a minority administration.

“We need to speak to the country with one voice – our voice,” he said. “And as such, I’m clear that today marks a new beginning for the SNP in government.”

But he immediately faced multiple questions about his own authority. This was a deal he previously claimed was “worth its weight in gold”. His support for it was part of his pitch during last year’s leadership contest. Just a couple of days ago, he was expressing hope it would continue. What changed?

Mr Yousaf said he had been thinking about it “for quite some time”, adding: “But of course, you’d understand that for me it was important to take some of that counsel in private. I’ve been speaking to people I trust.”

It didn’t escape anyone’s notice that Stephen Flynn, the SNP’s Westminster leader, was recently spotted in Holyrood. "Flynn has bounced the First Minister into this,” one SNP MP told The Scotsman. “It’s his party now.”

Mr Yousaf denied being a lame-duck leader, adding: “This is leadership. This is the ability to say we are taking control as a party and indeed as a government, on our priority terms, our policy terms.”

In a furious statement, the Greens accused the First Minister of “political cowardice” and insisted he could no longer be trusted. He had "sold out future generations", the party said. A source said the SNP had “shat it”.

Some compared it to a bitter divorce. And certainly, the anger and sense of betrayal was palpable.

The First Minister’s spokesman said a potential vote of no confidence had been war-gamed, but it was hard to believe they had seen this coming. Will he resign if he loses? “It’s a hypothetical, and that’s the business of the next week,” the spokesman said.

But even if he survives, the past few days have done nothing to combat the perception of Mr Yousaf as a leader battered by political currents, swept this way and that and unable to get a grip on events. There is a jarring disconnect between what he has said publicly in recent days, and the action he took on Thursday morning.

Opposition politicians are rubbing their hands with glee. “This is funny as f***,” one senior Scottish Labour figure said as I bumped into them on the way to Bute House.

Later, as Mr Harvie and his co-leader Lorna Slater told journalists why they were backing the motion of no confidence in the First Minister, figures from Labour and the Liberal Democrats could be seen among the gathered throng in the Scottish Parliament’s garden lobby, relishing every moment.

"I’m off for a pint,” one said gleefully when the press conference was over.

A fair number of SNP MSPs will be glad to see the back of the Greens. The party had not been universally popular on the Nationalist benches, to put it mildly. Kate Forbes, who came second to Mr Yousaf in last year’s leadership contest, said the SNP had an opportunity to focus on its priorities.

Fergus Ewing, the backbench rebel and long-term critic of the Greens, was slightly more effusive. “Oh happy day,” he said. “As Tony Bennett sang, you must believe in spring.”