Recent polling suggests National has suffered the largest decline in party-vote support since the 2023 election, falling by almost 10 percentage points. NZ First appears to be a major beneficiary, gaining around five points on its 2023 result. One explanation advanced for this shift is dissatisfaction among some centre-right voters who believe National has not moved quickly or decisively enough to reverse the policies of the Ardern–Hipkins government.
However, this election may be determined by more than the party vote. On 7 November, the outcome could depend on something considerably more complicated: the number of electorate seats won, the possibility of an enlarged Parliament, and whether TOP crosses the 5% threshold.
With opinion polls pointing to a close contest between the major political blocs, here are four things worth watching as the results come in.
1. The Māori Electorates — The Overhang
The seven Māori electorates could have an influence on the final parliamentary arithmetic far greater than their numbers suggest. The reason is a little-understood feature of MMP known as the overhang. Normally, a party's share of the nationwide party vote determines its total number of seats in Parliament. However, if a party wins more electorate seats than its party vote entitles it to, it keeps those seats. The additional seats create an overhang, allowing Parliament to expand beyond its normal 120 members.
Te Pāti Māori has been promoting a tactical vote splitting strategy, encouraging supporters to give their electorate vote to its candidates while giving their party vote to Labour or the Greens.
The potential advantage is clear. Labour and the Greens benefit from the party votes, while Te Pāti Māori could secure electorate seats beyond its proportional entitlement.
Consider a hypothetical example. If Te Pāti Māori receives 2% of the party vote, it would ordinarily be entitled to approximately three seats. But if it wins five electorates, it retains all five MPs, potentially creating two overhang seats.
The crucial election-night number is therefore not simply how many Māori electorates change hands, but how many Te Pāti Māori wins compared with its entitlement under the party vote.
2. . National's Party Vote — Could It Also Create an Overhang?
The same MMP provision could have significant consequences for National.
National won 43 general electorates at the 2023 election and subsequently won the Port Waikato by election, bringing its electorate total to 44.
However, National's party-vote support has fallen considerably since 2023. The October RNZ–Reid Research poll put National on just 25.9%, while other recent polls have generally placed it closer to 28–30%.
This matters because National could win more electorate seats than its party vote entitles it to.
Suppose National receives 28% of the party vote, giving it approximately 34 seats in a 120-seat Parliament. If it wins 40 electorates, it retains all 40 MPs, potentially creating six overhang seats. That could substantially alter the parliamentary arithmetic.
For election-night viewers, the important comparison is therefore between National's party-vote entitlement and the number of electorate seats it wins.
This possibility has prompted considerable discussion about strategic voting.
Harry Mowbray, through his website splityourvote.co.nz, has encouraged centre-right voters to give their electorate vote to National and their party vote to either ACT or NZ First. He argues that even a modest shift in party votes from National to its coalition partners could substantially strengthen the centre-right bloc's parliamentary position.
Reality Check Radio has also launched a series of Vote Smart videos explaining overhangs, strategic voting and the consequences of party votes that do not translate into seats.
For example, a party vote for the Opportunity Party would not directly elect any MPs if the party failed to reach 5% and won no electorate. Equally, if National wins more electorates than its party-vote entitlement, additional party votes for National may not translate into additional National MPs.
That is why the marginal electorates could be especially important.
3. The Marginal Electorates — The Close Contests
There are 64 general electorates and seven Māori electorates being contested this year. Following the 2023 Census, the Representation Commission revised electorate boundaries, with 49 general electorates and three Māori electorates having their boundaries adjusted. That means historical majorities may not directly translate to this election. For example, boundary changes have made the previously safe National seats of Kāpiti and Whanganui marginal.
Other marginal electorates held by National are Banks Peninsula, New Lynn, Hutt South (Held by Chris Bishop), West Coast-Tasman, and Mt Roskill.
On the other side of the ledger, Labour-held seats worth watching include Mt Albert, Henderson and Wigram. The contest in Tāmaki, currently held by ACT, will also be of interest.
If National is in an overhang position, winning or losing an electorate could change both its representation and the overall size of Parliament. That gives marginal seats an added significance this year.
Another to watch is Mt Albert. Labour has held the electorate since 1946, with former prime ministers Helen Clark and Jacinda Ardern among its MPs. However, in 2023 Labour’s Helen White defeated National’s Melissa Lee by just 18 votes, out of more than 38,000 cast. The National vs Labour contest has become even more interesting with two high-profile candidates competing for left-leaning votes: Green Party MP Ricardo Menéndez-March and Opportunity Party leader Qiulae Wong.
Boundary changes have also altered the electorate's composition, removing much of the traditionally left-leaning Grey Lynn area while adding parts of suburbs that have historically been more favourable to National.
4. The Opportunity Party — The 5% Threshold
Under MMP, a party must receive at least 5% of the nationwide party vote or win an electorate seat to qualify for proportional representation in Parliament. TOP has recently been polling close to that threshold.
The October RNZ–Reid Research poll put TOP on 5.5%, while the October Taxpayers' Union–Curia poll had it on 4.8%.
That 0.7-percentage-point difference could significantly affect the final parliamentary balance, especially given National's stated position that it would not work with TOP. On election night, TOP's party-vote percentage will be one of the most important numbers to watch.
At 4.9%, assuming it wins no electorate, TOP would receive no seats. At 5.1%, it could receive approximately six or seven MPs. That is a dramatic difference for a movement of just 0.2 percentage points.
In an election where the two main political blocs are polling so closely, the result could ultimately hinge on a combination of TOP's performance, the marginal electorates and the overhang provisions of MMP.