Green Party co-leader Metiria Turei says the party's political wing remains strong, despite the departure of Sue Bradford.
The MP left Parliament on Thursday after 10 years. Her departure was prompted by the failure of her bid for the position of co-leader, which was won by Ms Turei.
Senior politicians from other parties say her departure will be a loss to the Greens.
Ms Turei says that while the party is losing a powerful advocate, it still has plenty of experienced MPs.
Ms Bradford will be replaced by small business advisor Dave Clendon, of Auckland.