Split happens: Politicians reel as voters get the hang of the overhang

In brief

• National won 42 electorates but no list seats, producing a seven-seat overhang. Supporters could back National candidates while giving ACT or NZ First their party vote.

• Te Pāti Māori encouraged similar vote-splitting on the left, helping the Greens gain support in Māori electorates.

• Critics say overhangs undermine proportionality. But could tactical voting also give disgruntled voters greater leverage over party leaders and future list MPs?

Political establishment figures are crying foul and calling for MMP reform, arguing that organised vote-splitting has distorted proportional representation and may have decided who governs. 

But what if voters have discovered how to use MMP to punish parties that disappoint them, without handing power to the opposition?

The mandate National failed to satisfy

For National voters expecting smaller government, deeper spending cuts and a rollback of race-based policies, the last three years may have been disappointing. 

By giving their electorate vote to National and their party vote to ACT or NZ First, supporters could keep National's electorate MPs while depriving it of party votes needed to elect list MPs. Win more electorates than your party vote entitles you to, and an overhang is born.

National was warned

Former prime minister Sir John Key famously dismissed the strategy as “the opposite of clever”, warning that National could lose some of its most talented ministers.

He was right about the risk. But why would voters want to save ministers they believed had failed to deliver on the mandate of 2023? For some, losing those ministers may have been the point.

On the preliminary results, National won 42 electorates but just 29.21% of the party vote, enough for approximately 35 seats under proportional allocation.

The result is seven overhang seats, no National list MPs and the likely departure of senior figures including Gerry Brownlee, Chris Bishop, Nicola Willis and Paul Goldsmith.

Meanwhile, ACT and NZ First collected a combined 20.7% of the party vote.

Harry Mowbray, who promoted the split-vote campaign alongside Don Brash and Reality Check Radio, is convinced it made the difference.

“The campaign succeeded incredibly well,” he told Stuff. “This is 100% due to us. 100%.”

Not everyone agrees. Constitutional lawyer Graeme Edgeler has suggested National's overhang might have arisen organically from its declining party vote, while political commentator Bryce Edwards believes the campaign probably supplied the decisive margin.

For years, securing a high party-list ranking has offered a pathway to Parliament. But National's aspiring list MPs have just learned that loyalty to party bosses offers little protection when voters withdraw their support.

Could the threat of another split-vote campaign make MPs more willing to challenge their leadership when election promises go unfulfilled?

Party bosses control the list, but voters decide whether that list is worth anything. 

The left played the same game

Te Pāti Māori openly urged supporters to give its candidates their electorate votes while directing their party votes to Labour or the Greens, seeking an overhang that could help change the government.

Green co-leader Chlöe Swarbrick described the election's focus on strategic voting as “very cynical and very attack ad-y”.

Yet the Greens themselves benefited from vote-splitting encouraged by Te Pāti Māori. Their share of the party vote across Māori electorates surged from around 9% in 2023 to 36% in 2026.

Pollster David Farrar calculates that had Green support in Māori electorates remained at its 2023 level, the party would have won 14 seats rather than 16. Te Pāti Māori, meanwhile, won five electorates on just 0.57% of the party vote, creating four overhang seats.

The difference is that National's seven-seat overhang outweighed Te Pāti Māori's four, helping give the National-led bloc its slender preliminary majority.

The argument over whether MMP is being gamed looks rather different when both sides are playing.

Voters are learning the system

Social media, independent broadcasters and online political communities helped bring an obscure feature of MMP into public discussion.

Mainstream outlets also covered it, often critically. But voters could exchange information, debate electoral mathematics and organise independently of political parties and traditional media gatekeepers.

Thirty years into MMP, that growing electoral sophistication could change the balance of power between voters and politicians.

Is MMP really broken?

Overhang seats are permitted under MMP, even though they weaken the proportionality the system was designed to achieve. But proportionality is not the only democratic principle worth examining. Accountability matters too.

National's party vote has fallen sharply since 2023, while its electorate candidates have retained considerable support.

Perhaps voters weren't rejecting the centre-right. Perhaps some were rejecting National's particular version of it.

Before demanding changes to MMP, politicians might ask themselves why their own supporters felt compelled to use it this way.

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