The final week of voting is being seen as crucial for the Auckland mayoral contest despite some polls favouring Len Brown.
Two polls of people who have cast their ballots put him ahead of John Banks, with a reported surge of voting in Mr Brown's stronghold of South Auckland.
Among Auckland's largest wards, turnout in Otara, Papatoetoe and Mangere is near 30% compared with a regionwide figure of 25%.
Those communities voted strongly for Mr Brown when he won the Manukau City mayoralty three years ago.
Left-wing commentator Matt McCarten says enthusiastic Len Brown supporters have voted early, while less certain centre-right voters may be sluggish. However, he says, supporters of Mr Banks may vote more strongly in this final week and if turnout doesn't rise beyond 40%, he could win.