Scottish Greens MSP Ross Greer is reportedly set to announce his candidacy for a co-leadership position within the party.
The BBC reports Greer, the West Scotland MSP, will formally launch his bid later today.
Among the policies he will campaign for are tax increases on the most well off, as well as the expansion of free bus travel and other measures to reduce both the cost of living and carbon emissions.
In April, Patrick Harvie revealed he would not seek re-election, while his co-leader Lorna Slater does plan to run again.
Green party rules dictate leaders serve for two-year terms and that one of the co-leaders has to be a woman.
Gillian MacKay, who spearheaded the legislation to create buffer zones to limit protests around abortion clinics, has also declared herself a candidate.
The leadership contest is expected to be decided before Holyrood returns from the summer break.