Who will be New Zealand's prime minister after the 2026 election?

Both leaders have boxed themselves in with public promises. Winston Peters says NZ First won't do a deal with Labour, and in August Chris Hipkins answered by ruling out NZ First himself, citing what he called overt racism. Luxon, for his part, has ruled out working with the Opportunity Party. Those are costly signals because breaking them after the election would carry a large audience cost, and together they fix the two blocs in place.

Voters are unhappy with both major parties, and the pressure is concentrated on National. Reuters reported that the RNZ-Reid Research poll released October 6 put National at 25.9 percent, its weakest support since 2020. Luxon has ruled out working with the Opportunity Party, so he cannot widen his own path; his best case is Opportunity falling under the 5 percent threshold. Hipkins's incentive is the opposite: say little about Opportunity's demands and let the arithmetic work.

Reference class: New Zealand governments seeking a second term. Since 1935, only two governments have lasted a single term, both Labour, in 1957 to 1960 and 1972 to 1975. Counting the first-term governments since 1935 whose re-election bids have been decided, 9 of 11 won a second term, a base rate of about 0.82. No National-led government has ever lost after one term.

The closest analogue is 2023 in reverse: a first-term government with a weak major party, a strong NZ First and a fragmented opposition. It breaks because this time the minor parties are unusually large and the governing party is the one losing share. 1News reported that its late September Verian poll gave the opposition plus Opportunity 65 seats to 59 for the right bloc (a combined total above 120, which implies overhang seats from electorate wins), and Reuters reported that in the RNZ poll Luxon's bloc fell short of a majority with Opportunity pivotal. But interest.co.nz reported that the Taxpayers' Union-Curia poll taken October 1 to 5 had Opportunity just under the threshold and the current coalition with enough seats to govern. No National-led government has lost after one term.

Start where version 1 ended: the right bloc's poll-based chance of forming a government was about 0.53. Since then, three major polls have landed. 1News Verian and RNZ-Reid Research both put the left bloc plus Opportunity at a majority; Taxpayers' Union-Curia put the right bloc in government with Opportunity under the threshold. A split of two to one, with Opportunity's entry at the threshold deciding every case, moves the right bloc's poll-based chance down only slightly, to about 0.51, our calculation. Version 1's largest downward signpost required a left majority without Opportunity, and it has not fired.

Blend nine parts polls to one part base rate: 0.9 times 0.51 plus 0.1 times 0.82 gives about 0.54 for the right bloc, our calculation, still well below the 0.82 base rate for second terms. That departure is deliberate: the base rate comes from governments whose main party polled far stronger, while National now polls at its weakest level since 2020 and its bloc is short of a majority in two of three recent polls. Six weeks out, polls carry far more information than a reference class built on different party systems. Multiplying by about 0.92 for the chance National changes leader, and trimming for poll volatility, leaves Luxon at 0.47 and another National leader at 0.04. The left bloc takes 0.46, all to Hipkins, and 0.03 stays on other outcomes, our calculation. We put Luxon one point ahead rather than level because the most recent poll by fieldwork date favoured the right and because Opportunity must clear a hard threshold for the left to govern; that is a tiebreak, not a favourite.