Tasmania has suffered further political upheaval with longstanding state Greens leader Cassy O'Connor resigning for an upper house tilt.
Ms O'Connor, one of two Greens MPs in Tasmania's lower house, was first elected in 2008 via a countback and became leader in 2015.
She announced on Thursday she was quitting as leader and stepping down as member for the Hobart-based seat of Clark.
"This hasn't been an easy decision," she said.
"I love my job. I love working in parliament and especially in an exciting, dynamic, balance-of-power parliament. But it is time to go.
"It is the right time for the Greens. We need renewal in leadership and the House of Assembly."
Her departure comes after the Liberal government was plunged into minority in May when two MPs quit to the crossbench over concerns with the state's deal for an AFL club and stadium.
Premier Jeremy Rockliff oversees the only non-Labor government in the country.
There is speculation a state election will be held well before its June 2025 deadline.
Ms O'Connor said she intended to seek pre-selection for the upper house seat of Hobart.
A recount will be held to replace Ms O'Connor in Clark, with her seat expected to go to Greens candidate Vica Bayley.
Ms O'Connor served in cabinet alongside fellow Green Nick McKim, her partner who is now a senator, in 2010 under a state Labor-Greens government.
She was later given the human services, community development, Aboriginal affairs and climate change portfolios.
Ms O'Connor was the first Greens' female MP to serve in a cabinet position in Australia and delivered Tasmania’s working with vulnerable people legislation.
She said her proudest moment was voting for the Tasmanian Forest Agreement in 2013.
"That vote ... protected more than half a million hectares of some of our most beautiful forests," she said.
Former federal Greens leader Bob Brown described Ms O'Connor as a strong and wise defender of Tasmania's future, particularly its wild and scenic beauty, wildlife, Aboriginal heritage and visitor hospitality.
"She has been a champion for social justice and was the most innovative minister for housing Tasmania has seen," he said.
"Cassy was the real opposition leader in Tasmania, on a whole range of social justice and environmental issues in which Labor lines up with the Liberals."
Rosalie Woodruff will be acting state Greens leader.
Mr Rockliff said although he didn't see eye-to-eye with Ms O'Connor on some issues, she had been a passionate advocate for the Greens.
