People Before Profit (PBP) has invited former Green Party members to consider joining their organisation in an open letter.
The letter urges former members to examine PBP’s "eco-socialist policies" and to “enter a dialogue” with the Opposition party.
It comes as on Monday, South County Dublin Councillor Peter Kavanagh became another prominent member to resign from the Green Party, citing the "culture" of the organisation since it entered a coalition with Fianna Fáil and Fine Gael.
In the letter addressed to members of the Green Party, PBP criticised the coalition Government’s Climate Action Bill, describing it as “riddled with holes”.
It said the Opposition group was building a "principled and coherent party" that is "a natural home” for those seeking to address climate change.
“Basic environmental principles are being sold out and this government simply will not take the radical steps needed to deal with the climate crisis,” the letter said.
“The draft Climate Action Bill, for example, is riddled with holes and full of vague aspiration that will mean we cannot deliver the measures needed.
“But where do activists, who concerned about the unfolding climate and environmental crisis, go now?
“We are urging you to look at People before Profit and its eco-socialist policies. We think we are a natural home of all those who want to fight catastrophic climate change and for a truly Just Transition.”
The letter said PBP was seeking to build a “red/green movement” that will take climate and environmental concerns “into the heart of working class communities”.
It called for former Green Party members to contact the party to discuss progressing their "shared agenda".
A number of prominent councillors have resigned from the Greens in recent months. Lorna Bogue in Cork resigned in October last year, and last week Liam Sinclair in South Dublin and Sophie Niccollaud in Dublin City Council left the party.
Mayo-based European and Dáil candidate, Saoirse McHugh, also resigned last year.
