All bets could be off for Labour when it comes to winning the hotly-contested Wellington seat of Ohariu.

Green Party co-convener Debs Martin has confirmed the party will stand a candidate against Labour's Greg O'Connor.

O'Connor was expected to win the seat, after United Future leader Peter Dunne pulled out on Monday.

But the Green Party's decision to put to stand Tane Woodley in the seat could split the left vote, benefiting National candidate Brett Hudson.

United Future has also chosen to replace Peter Dunne with another candidate, Bale Nadakuitavuki.