The Labour Party's Auckland Central candidate, Jacinda Ardern, says electoral boundary changes will make her fight for the marginal seat even harder.
In the final electoral boundaries set by the Electoral Commission, Auckland Central loses the suburbs of Westmere and Grey Lynn.
Ms Ardern says at the last election, those suburbs had a good number of Labour supporters.
"If you do a booth by booth analysis based on the last election, certainly it would've still been a National win, absolutely. But it is still within what I would consider to be the bounds of a marginal seat.
"With a bit of hard work and enough of a swing, it is still entirely possible that that seat can be taken back - and that's what we'll be working for."
Ms Ardern lost to National's Nikki Kaye in 2011 by fewer than 1000 votes.