THE joint leader of the Scottish Greens has signalled support for an electoral pact with the SNP in a bid to secure a pro-independence majority at the Holyrood election.

Maggie Chapman said such an arrangement was “certainly possible”, but added that her party would need to go into any discussions with the SNP knowing what they would not give up “at any cost.”

However Pamela Nash, chief executive of the pro-UK Scotland in Union, said:

“Voters won’t take kindly to a pro-independence stitch-up. The Scottish Greens have given up fighting to build a greener world, and now just want to build a more divided world by helping their SNP bosses.

“The pro-independence parties will never stop campaigning for a divisive second independence referendum, and they will use every single vote for them as an excuse to pursue the break up of the UK.”

The SNP and the Greens command a pro-independence majority at Holyrood, but senior Nationalists believe there is no possibility of a second referendum before 2021.

Allies of First Minister Nicola Sturgeon believe her party and the Greens will have make an explicit pitch to voters at the next election on indyref2 and use any victory as leverage with the UK Government.

However, although both parties work closely together at Holyrood - the Greens have helped pass recent Budgets - they fight elections separately.

The Greens rarely contest first-past-the-post contests for the Scottish Parliament, but they fought Edinburgh Central in 2016 and won 4,644 votes.

SNP insiders believed this decision was key to Scottish Tory leader Ruth Davidson taking the seat with a 610 majority.

SNP MP Tommy Sheppard last week called for the Greens not to field a candidate in this seat: “I appreciate it’s a big ask and I don’t think the Greens should do it in all circumstances.”

He added: “What is the point in spending time and activist effort fighting a seat that you know you are not going to win if there is a serious and real chance of the Tories getting it because you split the vote?”

Both parties also chased pro-independence votes on the regional lists at the last Holyrood election, with the Greens winning six seats and the SNP securing another four MSPs.

Chapman, who along with Patrick Harvie is one of two Scottish Green party’s co-conveners, is also sympathetic to joint working.

Asked by this newspaper whether there could be an electoral pact or common understanding between the parties in 2021, she said:

“It is certainly possible. It is not something I would ever want us to rule out.”

She explained: “We would need to go into any of those discussions very clear of what it is we would be prepared to concede, what certain things would be our things that we would not give up at any cost.”

Asked whether it would be an attractive plan if it were to return a pro-independence majority, she replied: “For me, I think it would be.”

In the wake of the 2014 independence referendum, SNP MSPs backed pro-independence parties contesting the general election as either a "Yes Alliance" or a "Scotland Alliance".

Leaked emails from that time showed Edinburgh Pentlands MSP Gordon MacDonald writing:

"The next round is GE [General Election] 2015. What about getting agreement with Greens, SSP, etc and stand as YES Alliance? The unionist vote would split between Labour, Tory & Libdem. We would do decidedly better than the small numbers of MPs we got elected last time.”

Joan McAlpine, another SNP MSP, was also revealed to have responded: "I was thinking along the same lines.”

An SNP spokesperson said: "The SNP contests every seat in every Scottish election, and we are always prepared to work constructively with other parties in Scotland’s best interests.

“At the next Holyrood election we will work hard to win as many seats as possible - in the hope that people put their trust in the SNP to stand up for their interests as Scotland's government."