Humza Yousaf is to resign as Scotland's First Minister. 

His leadership has been in turmoil since his shock decision to terminate the Bute House Agreement and kick the Scottish Greens out of government.

The beleaguered SNP leader was facing two knife-edge confidence votes in Parliament this week. It looked increasingly unlikely that he would secure the support of enough MSPs to survive.

Labour, the Tories and the Lib Dems had all been clear that they would not back him.

Yesterday, the Greens indicated that not only would they vote for the motion expressing no confidence in the First Minister but that they would only oppose the motion expressing no confidence in the Scottish Government if Mr Yousaf resigned.

Given the tight arithmetic in Holyrood, Mr Yousaf’s only hope of getting through the week was to cave into demands from Alex Salmond’s Alba, but doing so would alienate his own ministerial team and backbenchers.

SNP sources suggest the First Minister could step down as soon as today.

Asked about the prospect of Mr Yousaf quitting, SNP MSP Michelle Thomson told the BBC's Good Morning Scotland: “I’m hearing the same rumours and I think we’re all waiting to see what the actual position is.

“I guess the rumours suggest that something is afoot, but I honestly can’t clarify because I’ve had no update nor, as I understand, have my MSP group, so I guess we’ll all hear definitively one way or another this morning.”

Ms Thomson - who was a key player in the leadership campaign of Kate Forbes - described the First Minister as an “honourable man” who is “well liked” within the SNP Holyrood group.

Scottish Green Party co-leader Patrick Harvie told BBC Radio 4’s Today that Mr Yousaf was no longer "in a position to be able to lead.”

He added: “I don’t think there is anything that Humza Yousaf will be able to say to restore the trust he has broken.”

The ex-minister later told BBC Radio Scotland that he bears no “personal ill will” against Mr Yousaf.

"I take no pleasure at all, none of us in the Greens do, in turbulence and chaos over the last week or two," he added.

“But it is clear that Humza Yousaf, in the decision that he made last week, has broken trust with the Scottish Greens, cannot command a majority in Parliament, and we stand ready to work with someone who can."

Once the First Minister resigns then, as per Section 46 of the Scotland Act, Holyrood has 28 days to fill the vacancy.

If there is more than one nominee, then the winner will be whoever secures a simple majority of votes in the chamber gets the job.

Even if there is only one nomination, there still needs to be a vote. With the SNP running a minority government they need at least one of the other parties to back their nominee or at least abstain. 

If a majority of MSPs vote against the SNP candidate then the vacancy remains unfilled.

And if the office of first minister cannot be filled after 28 days, then an extraordinary general election takes place. 

More to follow...