Green MP Kevin Hague is quitting Parliament to take on the top job at environmental organisation Forest and Bird.
The party confirmed this afternoon that Hague, the Greens' third-ranked MP, had accepted the chief executive position at Forest and Bird and would be resigning as an MP.
He will be replaced by Auckland-based candidate Barry Coates, the former executive director of Oxfam New Zealand.
Greens' co-leader Metiria Turei said the party was sorry to be losing Hague, who had "worked tirelessly and effectively" for the party.
"We will miss his passion and his wisdom," co-leader James Shaw said.
Hague ran for the male co-leadership of the party last year, but was defeated by Shaw, a relative newcomer.
The West Coast-based MP was respected on both sides of the House, and would have been a certain minister in a potential Labour-Greens Government.
Among his biggest victories were lobbying for a culture change at ACC in 2012, and playing a leading role in the legalisation of same-sex marriage the same year.
Turei said his successor, Coates, will bring extensive experience in social justice, climate change and Pacific issues.
"He will be an important new voice in Parliament and we look forward to working with him."