Green Party co-leader Russel Norman has attacked the Government's Auckland super-city plan as a "hostile takeover" that could knock National out of power.
Dr Norman told the party's annual meeting in Dunedin on Sunday that the super-city plan will hand over control of $28 billion in assets to 20 councillors who will be free to push a privatisation agenda.
He said the super-city plan will "alienate everyone in Auckland".
Dr Norman, who is standing for the Greens in the Mt Albert by-election, said National's candidate, Melissa Lee, "has come to represent the incompetence and prejudice of the party".
He also took aim at Labour, attacking its record in power on everything from public transport, to poverty and levels of overseas aid.
The Mt Albert by-election is to be held on 13 June.