The Scottish Greens plan to persuade left-leaning SNP supporters to back them with their second vote at the Scottish elections.
The party’s co-convener Patrick Harvie said there is a “strategic opportunity” to approach those who will use their constituency vote for the SNP but who realise a regional vote for the nationalists “may not be worth very much”.
The Greens plan to target these regional votes with their policies on issues such as land reform and fracking as they attempt to send a record number of MSPs to Holyrood.
SNP members called for the party’s land reform policy to be more radical at its conference last year - with many aligned with Green proposals to prevent offshore tax avoiders from owning land while some party supporters also want a full ban on fracking, the controversial gas drilling practice which is currently subject to a moratorium.
“Unless the polls do something extraordinary over the next few months, I think many people recognise that a regional vote for the Greens is something worth contemplating,” Mr Harvie said.
The SNP is on course to win nearly all of the 73 constituency seats elected using the first-past-the-post system, according to opinion polls.
The party is also set to gain the largest number of votes on the regional list vote under the additional members system but would be rewarded with fewer seats than some of the other parties due to the way the system works.
The Greens - who backed independence at the 2014 referendum - won a record seven seats in the 2003 elections but have since failed to match or better that number.
“We think we can do better than that this time, given that strategic opportunity of being able to approach people who have a regional vote that they know won’t be of much value to the SNP, but they want a political party that will speak to some of the issues they care about,” Mr Harvie said.
“Many of the SNP members who want a bolder land reform agenda, who want a full permanent ban on fracking, know that they will get progress on those issues ... when the SNP know that the votes are not in the bag, when the SNP feel that they are under pressure, constructive pressure, from the other parties.
“I think we have the chance to persuade people to do something really interesting with the Parliament rather than the Government.”
The pro-independence left alliance Rise is also hoping to capitalise on the second votes of SNP backers.
Mr Harvie said: “Without any hint of being hostile to Rise, I don’t think that they will make life difficult for us.”