STEPHEN DAISLEY: The plain truth is, Humza's history

The next 48 hours will decide whether the Government stands or falls. Humza Yousaf has to cobble together 64 votes to survive a motion of no confidence in his first ministership.

His party will have to choose between backing a lame duck leader and preserving their government under a new figurehead. The parliamentary arithmetic is achingly tight; there is no room for error. This is politics at the highest stakes.

We might never know what possessed the First Minister to eject the Greens from his government so abruptly, or why he thought there would be no reprisals for this action, but his myopic strategy has rebounded with potentially fatal consequences for his political career. Banquo's ghost haunts harder when it has seven votes.

Now Yousaf has to patch together some kind of deal to keep himself in Bute House. This is no mean feat given the interests that must be balanced, all of which are in competition and some of which appear irreconcilable. Every potential compact to save him threatens to enlarge the coalition of those who want to sack him.

The most immediate threat is the confidence motion tabled by Douglas Ross. This is seeking to withdraw MSPs' support for the First Minister personally. If Yousaf lost this ballot, he would be under no legal obligation to resign but his position would be politically untenable.

Another motion, tabled by Anas Sarwar, would remove parliamentary confidence in the government. This does come with a legal obligation. Section 45(2) of the Scotland Act 1998 says that the First Minister must tender his resignation to the sovereign 'if the parliament resolves that the Scottish Government no longer enjoys the confidence of the parliament'.

If that happens, Holyrood has 28 days to appoint a new First Minister, or an extraordinary Scottish election must be held.

The differences between the Ross and Sarwar motions might seem esoteric but one distinction is crucial: Ross's resolution is more likely to topple the First Minister without forcing an early election. Neither the SNP nor the Tories wants an early election because the polls show both would lose seats.

For the Ross motion to succeed, it requires only a simple majority. Since the SNP has 63 seats, and assuming all its MSPs vote to back their leader, Ross needs 64 members to vote for his resolution.

As luck would have it, the Tory, Labour, Green, Lib Dem and Alba seats combined total 65. However, if Yousaf can convince just one of those opposition MSPs to swing in behind him, the vote would be tied 64-64. By convention, the Presiding Officer would cast a tie-breaker vote in favour of the status quo. Yousaf would live to fight another day.

One vote. Sounds straightforward enough. Except this is Scottish politics; nothing is ever straightforward. Alex Salmond's Alba Party, represented in Holyrood by Ash Regan, says it will back Yousaf in exchange for an electoral non-aggression pact. This would involve the SNP giving Alba a free run in certain seats.

Unsurprisingly, Nationalist sources have ruled out any such arrangement, with one insider branding it 'a fantasy'. Even if he wanted to strike a deal, Yousaf's MSPs and his grassroots members would not allow him. Salmond is reviled inside the SNP these days so teaming up with him is a non-starter.

This is doubly so given Alba's opposition to gender self-identification and support for women's sex-based rights. A not insignificant segment of the SNP would sooner lose a leader – and maybe even government itself – than abandon the party's current stance on transgender issues.

To complicate matters further, accepting Alba's help would essentially sacrifice any chance of a rapprochement with the Greens. Patrick Harvie and Lorna Slater's party have said they have no confidence in Yousaf but could support the Scottish Government on the Sarwar motion.

What they're after is regime change. Ditch Yousaf in favour of someone more to our liking, they are essentially saying, and the SNP will be home and dry. Because of the premium the Greens place on gender policy, any government they prop up will need to continue in the Sturgeon-Yousaf vein. Backing away from the gender agenda would mean having to forgo Green support.

Which leaves Yousaf with very few choices. He could try to re-establish relations with the Greens, perhaps by offering them a Bute House Plus deal under which they get everything in the Bute House Agreement as well as some fresh goodies to make up for his dumping them.

But even if the Greens could be convinced to resume co-operation with a Yousaf-led Scottish Government, it would represent a humiliating U-turn by the First Minister. He would be rebuilding bridges with the Greens just days after blowing them up.

More outlandishly, he could try to paste together an arrangement with the Lib Dems, maybe offering a ministerial position to Alex Cole-Hamilton, but even if Cole-Hamilton would go for that it is unlikely the membership – of the Lib Dems or the SNP – could be brought on board. Alternatively, he could woo a single Tory or Labour MSP to vote with him, but anyone who did that would immediately become a pariah within their party.

All of this is so much inside baseball. MSPs, special advisers and political journalists exchanging gossip and theories and wishful thinking. The plain truth is that Humza Yousaf is finished.

He was finished the moment he sacked Harvie and Slater. There is no way for those sackings to stand and Yousaf to remain in post. There is no way for them to be undone without undoing the man himself. There is just no way back from any of this.

The notion that convincing Regan or any other single opposition MSP to vote with him would be a victory is ludicrous. Engineering a draw is not a win. By definition it would mean the First Minister cannot command the support of a majority of MSPs. He would be mortally wounded.

He might be able to limp on for a while longer but what happens when he needs to pass contentious legislation or a budget Bill. Where is his majority going to come from?

Humza Yousaf's premiership is over. Whether he goes this week, in the weeks to come, or after a general election in which the SNP stands to lose almost half of its MPs, is nothing more than a matter of timing. The removals van is heading for Bute House. We're just waiting for them to assign a slot.

Of course, it would be in the interests of Unionists for Yousaf to stay, for no one is landing as many blows on the SNP as the party's leader. It's not every first minister who serves as leader of the opposition too.

But everyone in the SNP with any political nous knows the bloke's done for. It is in the party's interests to show him the door and replace him with someone who can work with both the Greens and the SNP's anti-Green backbenchers.

That in itself will be a challenge, and no one should assume that removing Yousaf will make the SNP's many problems vanish. The best they can hope for is that whoever replaces him doesn't make those problems so much worse, as Yousaf constantly does.

Humza Yousaf's leadership has been a year-long self-inflicted wound for the SNP, the party's very own Liz Truss premiership extended over multiple lettuces but no less damaging. There's no saving Yousaf. The SNP needs to focus on saving itself.