Scottish Green co-convener Patrick Harvie has called for Scots to vote for constructive critics and not more SNP "cheerleaders".
Harvie, who has served as an MSP for 13 years, rejected the charge that his party would be limited in their criticism towards the SNP due to their shared support of independence.
Speaking on BBC Radio Scotland's Good Morning Scotland programme, he said: "I'm sure the Labour Party wouldn't feel that they are curtailed in their ability to hold the Conservative government to account because they were on the same side in the independence debate.
"This is an election. It's not a binary choice about whether you support independence or not.
"I think many independence supporters saw during the referendum campaign a distinctive platform for the Greens that they found attractive and many people who weren't yet convinced by independence but might one day clearly need to hear something more than what the SNP had to offer.
"When ministers sit across the table in committees promoting a range of Bills, do you want them held to account only by their own cheerleaders, by people who will only ask them easy questions, or people who put constructive pressure to bear and try and make sure Scotland becomes a better place.
His comments came under criticism from Scottish Labour who questioned the Scottish Greens' record in opposition.
Scottish Labour’s enviromental justice spokeswoman Sarah Boyack said: "Scottish Labour has outlined plans to ban fracking in Scotland and has been the only party to consistently challenge the SNP on their failed record on climate change as well as their plans to slash Air Passenger Duty, which will pump 50,000 tonnes more emissions into our atmosphere every single year.
"It is disappointing that, when presented with the opportunity to back Labour's plans, the Greens voted with the SNP instead, despite having a manifesto commitment to using the Parliament's tax powers."
SNP MSP Sandra White said: “The SNP has a record that we are proud to take to voters: NHS spending is at a record high; crime is at a 41 year low; youth employment is at the highest level for a decade; and we have met our target to build 30,000 affordable homes.
“In this election we seek an unprecedented third term to build on this record of achievement and deliver our bold vision for Scotland’s future – the only way to guarantee that Nicola Sturgeon is re-elected as First Minister is to cast both votes SNP.”
Opinion polls show that many voters who are planning to vote for the Scottish Greens on the regional list will vote SNP with their constituency vote.
The Scottish Greens currently have two MSPs but are hopeful of increasing their number at May’s Holyrood election. The previous high watermark of the party’s support was seven MSPs in 2003 election.
Report by Aidan Kerr, STV’s digital politics reporter. You can contact him at email@example.com.