Patrick Harvie has argued that votes for the Scottish Greens at the next general election should be counted as part of Nicola Sturgeon's mandate for independence.
The First Minister wants a referendum to take place on October 19 next year but many experts believe Supreme Court judges will rule her government lacks the powers to stage such a vote.
The SNP leader last week announced her Plan B would be to use the next UK general election as a "de facto" referendum where her party would campaign on the single issue of independence.
READ MORE: Sturgeon hails 'encouraging' poll which shows Yes campaign edging ahead
Questions have been asked on whether this would mean the SNP would have to achieve over 50 per cent of the total votes cast in Scotland on its own - or whether votes for other pro-indy parties would also be included.
Appearing on BBC Scotland's The Sunday Show, Harvie said Greens votes should count.
"It's clearly preferable that Scotland's democratic mandate is respected," he said.
"One of the big questions for the other side of this debate is - if repeated pro-independence majorities in both parliaments isn't enough for a mandate, what on earth is?"
"If they do continue to refuse to accept that, we'll go to court to seek permission to take that referendum forward without it.
"If the answer is no, we are going to have to use the following UK election, if that is the only ability we have then, to put the question to the public."
Harvie said it would be the decision of local party branches on whether Green candidates would stand in every constituency.
Asked if his party's candidates would fight an election on the single issue of independence, Harvie said: "Greens offer a distinct vision of what kind of independence would want.
"Greens, the SNP and other campaigners who support independence don't necessarily agree on the policies for after independence, so we want that rich diversity of ideas to come forward."
He added: "We would be setting out a Green vision for an independent Scotland and we would be accepting the premise that a majority of votes for pro-independence parties and candidates needs to be respected as a mandate."
Asked how Green votes can be used for a mandate if his party did not stand on the single issue of independence, he continued: "This is why a referendum is clearly a preferred route.
"I think the other side should respect we have been pushing this for a very long time.
"If this is where get to, and an election is the only route to establishing that mandate, in those circumstances, we will have to say that a majority of votes for pro-independence parties has to be respected."
Sarah Boyack, Scottish Labour constitution spokeswoman, said: "This shows what many of us have suspected for some time – the Scottish Green party is more than happy to drop their environmental priorities to focus solely on independence.
"Faced with a climate crisis, the Scottish Green Party is deciding to put flags before the future of our planet.
"This is a betrayal of the thousands of environmentalists who oppose the break-up of the UK.
"The focus of all of Scotland’s politicians must be on re-building our NHS, our economy, our public services and tackling our climate crisis."
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