Lorna Slater has suggested the Scottish Greens could prop up a unionist government at Holyrood – opening the door to potentially crowning Anas Sarwar as the next first minister.

The co-leader of the Scottish Greens said that independence is not a red line for her party going into co-operation with other parties at Holyrood.

In August 2021, the Greens and the SNP, both pro-independence parties, signed the Bute House Agreement, giving then-first minister Nicola Sturgeon a majority government at Holyrood.

The two parties are able to disagree on some policies that are exempt from the Bute House Agreement.

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Polls suggest that Labour’s surge in support and a fall in favour of the SNP has put both parties neck and neck for Scottish Parliament voting, despite being more than two years away from the next Holyrood election.

But current polling suggests that both the SNP and Labour would need the support of other parties to form the next Scottish government.

Ms Slater was asked if her party would rule out forming a coalition or co-operation with Scottish Labour in principle over their differing stance on independence.

Appearing on the BBC’s Sunday Show, Ms Slater was asked if the Greens could "go into government with another party” and “if Labour needed your support to get Anas Sarwar elected as first minister, could you do that or is independence the red line?”

She said: “The Greens are open to conversation wherever we have points in common.

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“I think the challenge for Labour is what do they have in common with us, because it’s hard to know what they stand for at the moment.”

Asked again if independence isn’t necessarily a red line”, Ms Slater said: “Absolutely not.”

Tensions between the SNP and Greens have frayed in recent weeks over First Minister Humza Yousaf’s announcement at his part conference that council tax will be frozen next year.

The Scottish Greens have raised concerns over local authorities being properly funded by Holyrood to make up the difference in cash that will no longer be able to be tallied up from hiking the charge.

Ms Slater has personally criticised the council tax announcement, with the Greens remaining committed to council tax reform.

The minister has called for a timetable for the overhaul to finally take place, with a pledge initially being made when the SNP came to power back in 2007.

Also speaking on the Sunday Show, she warned that “we need to keep our eye on the prize” of reforming the charge.

Ms Slater added that “the First Minister has committed to starting that process, to make the council tax in Scotland fairer, more progressive and most importantly, to fund our councils properly for the long-term”.

She said: “I’m looking forward to getting started on that project.

I’d like to see a timeline and process put forward for this so that the public can see movement on it.”

But Ms Slater admitted that “it has been stuck far too long in a regressive council tax that just isn’t working for councils and isn’t working for Scotland”.

She said: “Changing council tax is indeed a difficult thing to do – it absolutely needs the momentum. Government after government has failed to do it. Our councils need properly funded.

“We need to make sure that taxation in Scotland is fair and progressive so we are not burdening those who can least afford to pay.

“This is a big project, a core value for the Scottish Greens, and we are absolutely going to get stuck in.”

In recent months, some within the SNP including backbench former minister Fergus Ewing, have called for the Bute House Agreement to be torn up – blaming the Greens for policy problems and claiming it is harming the SNP’s reputation.

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Mr Ewing was suspended by the SNP for voting against the party whip in backing a motion of no confidence in Ms Slater.

Scottish Labour declined to comment on the specific proposals by Ms Slater when asked by The Herald.

But Mr Sarwar has previously suggested ruling out forming coalitions with other parties if he is successful in the next Holyrood election.

Speaking at the Labour party conference in Liverpool earlier this month, the Scottish Labour leader said he would form a minority government if he wins the next Holyrood election.

He said: “We would be looking to go into that election to form a government in our own right, a minority Labour Government.

“I think we wrongly viewed pre-2007 that we couldn't do minority government.”

Ms Slater was also asked whether turncoat MSP Ash Regan was correct in claiming that independence is not a priority for the SNP anymore as she left the party to join Alex Salmond’s Alba party.

The Greens co-leader said: “No, she’s not right.

“Independence is, of course, foundational to everything we do in government, we do in the Scottish Greens.”

Ms Slater added: “I can’t speak for any other political party, of course, but so often in my job every day, when we’re trying to put in place support for industry or even support for households, the answer is we can’t do that – it’s not devolved.

“All of that is because of the dissatisfactory settlement we are in where most of the levers that we need for economic and green transition actually sit in Westminster with Rishi Sunak.”