THE Scottish Greens yesterday sent a message to the next SNP leader that committing to progressive values will be a “necessity” if the parties’ powersharing agreement is to continue.

Co-leader Patrick Harvie said the party was standing a “major juncture” as its spring conference took place in Clydebank, two days ahead of the announcement of the winner to succeed Nicola Sturgeon.

The continuation of the landmark Bute House agreement with the SNP – which saw the Greens enter ­government for the first time in the UK and gives the SNP a majority at Holyrood – is potentially under threat depending on who becomes the next first minister.

The result of that ballot will be ­announced tomorrow, with ­Scottish Finance Secretary Kate Forbes, Health Secretary Humza Yousaf and former community safety minister Ash Regan running for the top job.

Yousaf is the only one who has ­committed to challenging Westminster’s veto of the Gender Recognition ­Reform Act passed by Holyrood, with a failure to do so being seen as a “red line” for the Greens.

Regan has explicitly ruled out court action, saying she believes the Scottish Government will lose, while Forbes has said she will first take ­legal advice on any challenge.

Forbes has also signalled that as first minister she would scrap plans for more protected ­areas in Scotland’s waters, where fishing would be banned, which is a part of the Bute House agreement.

However, she has said she wants to work with the Greens and have an “early conversation” with the party leadership.

Harvie was met with loud ­applause when he told members at conference: “We need to be clear that a sincere commitment to progressive values cannot be an optional extra in a choice of first minister – it is a necessity.”

He went on: “And it’s not just the policies and the values. It’s also about the constructive way of ­working that’s written into the Bute House ­Agreement – genuinely both sides seeking common ground.

“Yesterday I’m told that Kate Forbes said that she wanted to ­continue working with us, even though she has made it clear in a ­televised debate that working ­together simply meant us ­accepting her agenda – that’s ­hardly the spirit of co-operation.

“But there is so much more to what we can deliver if, and only if, we see a first minister who shares our ­commitment to the ­progressive ­values, the genuine spirit of ­co-operation, and the bold policy ­programme that runs through the agreement that you ­approved.”

Party co-leader Lorna Slater said the Greens had “unfinished ­business” and she wanted the party to stay in government to see further changes – but this would not be “at any cost”.

“We will never be a ­party that is prepared to put our principles to one side,” she said.

“We will only vote for the SNP’s new leader to become first minister if they are committed to the politics of co-operation.

“If they respect and share our ­values of equality and ­environmentalism. If they will prioritise climate justice.”

She was met with cheering as she added: “And if they agree that trans rights are human rights and that our trans siblings cannot be used as ­political fodder by Westminster.

“These are fundamental issues for us. They are non-negotiable.”

A question and conference ­session on the Bute House agreement took place during the one-day ­conference, with the party’s co-leaders and MSPs answering queries put forward by members.

The discussion centred more on how to make progress on policy ­issues such as bus, train and bike travel, drug deaths and ramping up climate targets rather than the future of the agreement.

There was a question on whether the Scottish Greens should try to ­negotiate more from the next first minister. And one member asking what would happen to rent controls in if it is Regan or Forbes who is elected seemed to reflect the mood in the room when he added “God help us”.

The concern was echoed by other attendees at the conference, who said the SNP leadership contest had actually led to them joining the Greens, One said: “It was a driving force for me for joining the Greens that my ­local SNP MSP expressed support for Kate Forbes.

“A lot of people are doing this whilst claiming to be LGBT allies, and to me, that is something you can’t do. On social justice, we are not ­doing as well as a lot of people seem to think we are.”

Another member said it had been “immensely reassuring” to hear the leadership of the party give an “unequivocal message” to the SNP about what would be required for the ­powersharing agreement to continue.

On a campaign visit to Dundee, Yousaf yesterday said the agreement would be one of his “first priorities” if selected as leader and said co-operation with the Greens will be needed.

“If you don’t, you end up not just in a minority government, but I have to say one of the most toxic parliaments I’ve ever been in, in terms of, I’m afraid, the opposition who will not look to co-operate with the SNP very often, even if there’s a good reason to do so,” he added.