National's candidate in the Mana by-election, Hekia Parata, says a call by independent candidate Matt McCarten to lift the minimum wage to $15 an hour is unaffordable.
The Unite Union boss says a high number of the Maori and Pacific workers in the electorate are on the minimum wage and the policy would have a substantial impact.
But Ms Parata says it would hit businesses in the electorate hard. "[It] opens a whole lot of questions about how affordable it is," she says.
Ms Parata says, however, that she's unsure whether Mr McCarten's run will take enough votes from Labour to allow her to win the seat.
Polling day is 20 November. The seat is a Labour stronghold.