Zack Polanski has said the far-left Greens are out to ‘replace’ Labour at Holyrood.
The ‘eco populist’ leader of the party south of the Border said radical Greens would ensure the ‘fairer’ country Labour had promised but never delivered.
Polls suggest the Greens, whose coalition with the SNP was marked by a series of high-profile policy flops, will come only a handful of MSPs behind Scottish Labour in May.
At an activist event in Glasgow on Thursday night, Mr Polanski said: ‘With Labour failing and disappointing people on so many levels, more and more people are looking to the Greens for the first time.
Zack Polanski believes the Greens can replaced Labour in the Scottish parliament
‘We don't just want to beat Labour, we want to replace them and build the kind of fairer, greener country that Labour has long promised but will never deliver.
‘It is the Greens who are standing for hope and the bold change that is needed.’
He also threw his weight behind Scottish Green candidates standing in May, one of whom wants to abolish prisons.
Scottish Greens co-leader Gillian Mackay said: ‘Zack is a fantastic and powerful voice for change and we are proud to have him in Scotland.’
Scottish Labour was asked for comment.