Green Party leadership hopeful David Hay claims he is being prevented from challenging party co-leader Russel Norman by being blocked from the party list.
Mr Hay said the party's candidate selection committee had recommended he not be given a place on the party list to contest next year's general election.
A Green Party spokesperson said Mr Hay's claims were clearly a case of sour grapes. The party committee assessed all the potential candidates and had decided he would not be suitable to represent the Greens.
The spokesperson said that decision was made in early October, well before Mr Hay publicly announced his intention to challenge for the co-leadership.
It is understood the committee will meet in Auckland on Saturday to make its final decision about his selection.