Herald’s poll of polls shows Christopher Luxon’s big gamble

The most likely post-election government formation in the Herald’s poll of polls is the one that was taken off the table by National leader Christopher Luxon this week.

The Herald’s poll of polls works by using data from a number of different pollsters and running multiple election simulations from gives a 99.91 per cent probability National, Act and Te Pāti Māori being able to form a government if the election were held this weekend (dropping to 93.51 per cent if the election were held on polling day, October 14).

But that grouping has been rendered highly unlikely after Luxon ruled out working with Te Pāti Māori this week.

That means the next most likely possible governing formation is a Labour-Greens-Te Pāti Māori agreement, with a 78.44 per cent probability if the election were held this weekend (dropping to 57.57 per cent if you extend the simulation to October 14).

A National-Act Government has a 47.67 per cent probability if the election were held this weekend (rising to 53.62 per cent for an October 14 polling day).

The odds of a Labour-Green Government look very slim indeed. It has a 0.7 per cent probability if the election were held this weekend, rising to 10.47 per cent if you extend the simulation to polling day.

The poll of polls runs using most political polls published in New Zealand and was updated this week to include the latest Taxpayers’ Union-Curia and Talbot Mills polls.

Te Pāti Māori run strong electorate campaigns in the Māori seats and have historically caused Parliament to have an additional or “overhang” seat because the number of seats the party won from its electorate races was greater than the number of seats won through its party vote performance. This overhang seat gives an advantage to whichever bloc Te Pāti Māori decides to back.

Currently, the poll of polls reckons Te Pāti Māori will win four seats thanks to its party vote, meaning an overhang would only be triggered if Te Pāti Māori won more than four electorates, something the party has done just once.

For each electorate seat Te Pāti Māori wins above four, the chance of a National-Act Government reduces.

If Te Pāti Māori wins four electorates the odds of National and Act governing alone drop to 45.1 per cent, if Te Pāti Māori wins five electorates the odds of National and Act governing alone drops to 34 per cent.

If the party wins seven electorates, the total number of Māori electorates, the likelihood of National and Act forming a government drops to 14.2 per cent.