Te Atatu MP Chris Carter has given his vote in Parliament to the Green Party to cast when he is absent from the House.
Mr Carter, a former Labour Party MP, says he would have preferred to cast his vote with Labour, but it has proven impossible.
He says his vote was cast by Labour only on an irregular basis, and he has had no response from the party's whips about the matter.
Mr Carter says he has come to an arrangement with the Greens to cast his vote for him.
The deal means Mr Carter must inform the Green Party of how he wishes to vote by 1pm the day before, otherwise his proxy vote will be included with the Greens' vote.