With the November 7 general election now just over two months away, and party campaigning about to start in earnest, political polls are coming into sharp relief.

Since the 2023 election, which saw a Labour majority government defeated by a right-wing coalition of National, NZ First and ACT, New Zealand’s mixed member proportional (MMP) system has settled into a broadly left-right split.

Based on the all-important party vote, the choice has been between a right-wing coalition of National, ACT and NZ First, or a left-wing coalition of Labour, the Greens and Te Pāti Māori.

But the rise in the polls of the centrist Opportunity Party has seen that dynamic begin to shift, suggesting the party could be in a kingmaker role after the election if current trends continue.

I’ve calculated a right-minus-left number for all polls since July using the Wikipedia polls table. While Labour leads National in some polls, National’s allies (ACT and NZ First) have a greater combined vote than Labour’s allies (the Greens and Te Pāti Māori).

Te Pāti Māori is below the 5% threshold in national........

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