Constitutional law expert Andrew Geddis examines whether the NZ First leader could really become prime minister, with the help of political nerds’ favourite TV show

Could life be about to imitate art, with Winston Peters reprising the lead role in what should be every true political nerd’s favourite television series?

No, I’m not suggesting Winston aspires to be a Frank Underwood figure, from the (seriously overrated) US House of Cards; much less Francis Urquhart from the far-superior (because, older and Britisher) BBC version. Nor is Winston’s admittedly sharp tongue quite up to Malcolm Tucker’s standards of abuse. I mean, calling media commentators “smart alec, arrogant, quiche eating, chardonnay drinking, pinky finger pointing snobbery, fart blossom” is both funny and accurate, but it still is no “please could you take this note, ram it up his hairy inbox and pin it to his fucking prostate”.

Rather, there’s been some recent speculation that Peters might try and take on the part of Birgitte Nyborg from the excellent Danish series Borgen. It’s not even a mild spoiler to remind you that, at the start of season one, a TV election debate unexpectedly results in Nyborg’s “Moderate Party” surging in the polls. As a result, Nyborg finds herself the Danish “Statsminister”, and the show then proceeds to brilliantly unpack over three seasons the personal and political toll that running a government exacts.

Of course, Birgitte Nyborg and Winston Peters are about as far apart from each other as you could possibly get. One is a compassionate, idealistic, moderate and reasonable leader who seeks to govern by consensus. The other wears pin stripes and has been found to be in contempt of parliament.

What they one day could have in common is that Peters may replicate Nyborg’s trick of becoming head of the government without leading the largest party in it. For again recall that despite their unexpected success in season one, Nyborg’s Moderates were (according to Wikipedia) only the third largest party in the Danish Folketing. Yet that didn’t stop her being able to take over the top job in the Christiansborg Palace.

Even though we’re well over a year away from an election here in NZ, the recent signing of a “Memorandum of Understanding” between Labour and the Greens had Tracy Watkins speculating (albeit very speculatively) that this document could be the harbinger of a similar Winston Peters prime ministership.

It might seem outlandish to give the keys to the ninth floor of the Beehive to a minor coalition partner. So too, seemingly, would be installing as prime minister someone who has nothing like the popular support of the major opposition leader.

But these are all scenarios that MMP makes possible.

Well, Watkins is right that MMP makes this outcome possible, just as Denmark’s proportional representation system allowed Nyborg to fictionally lead that nation. Because there’s nothing in our legal or formal constitutional arrangements to absolutely rule it out.

Our statutes only say that the prime minister first must be an elected member of parliament. And then our underlying constitutional principles require that the prime minister enjoy the “confidence of the House”, meaning that they obtain a majority (but not necessarily an absolute majority) on every “question of confidence or supply”. So if the parties in a governing arrangement — that is, any group of parties with a majority of the seats in the House — collectively agree to put their MPs’ votes behind the leader of a smaller party, then that leader automatically is recognised as PM.

Accordingly, there’s nothing to formally stop Winston Peters becoming prime minister following the 2017 election, even if New Zealand First was the third largest party in parliament – or even the third largest party on the government side, for that matter. Just as there’s nothing to formally stop Peter Dunne or David Seymour becoming prime minister in a governing arrangement with National.

But the sheer absurdity of those last two examples indicates the political and practical constraints on Winston becoming PM. Politically, the idea of a PM from a party that is not the largest on the government side runs counter to public expectations. We just assume that the leader of the party that “won” the election will be the country’s leader. For example, check out Te Ara: The Encyclopedia of New Zealand, which bluntly states: “The prime minister is the leader of the largest political party that governs the country”.

That expectation is something of a hangover from our First-Past-the-Post voting past. And it’s the same view that John Key sought to exploit back in 2013 when he spoke of the largest party in parliament’s “moral mandate” to form a government. I wrote back then that any attempt to claim a moral basis for the “largest must rule” claim was wrong. But as others have argued, the picture is a pretty nuanced one, given how the public generally expects its election processes to work.

In addition to public expectations, there would be real practical problems with having a PM from a smaller party. We have come to think of the PM as something like a US President, able to wield substantial political power in her or his own right. The constant focus on “John Key’s National government” (and “Helen Clark’s Labour government” prior to that) feeds that view.

In reality, however, PMs have to govern through their cabinet. They may have grown to be more than “first amongst equals” in that body, but they can’t simply impose their will upon it on every issue. Instead, there will be some issues where even John Key (or Helen Clark before him) must give way to the views of a majority of his (or her) colleagues. And those colleagues, remember, are from the same party that chose him (or her) as their leader.

What, then, if Winston were PM? Even on its best day, it’s hard to see NZ First getting more than around 15% of the party vote. Which would mean NZ First realistically could claim only a minority of the seats around the cabinet table, requiring Winston to preside over a collective decision-making body where his people can be outvoted constantly.

You may very well ask whether Winston has the sort of personality that would deal well with being overruled by his cabinet colleagues on a frequent basis. Equally, you may very well ask if anyone could serve as PM, having to front repeatedly for collective government decisions that she or he disagrees with.

That is why, enjoyable script-writing scenarios notwithstanding, I don’t think we’re likely to see Winston Peters in the PM’s office post 2017. We expect our PMs not only to be figureheads for the government, but actual leaders of it. And a PM who can’t get his or her way in cabinet most of the time simply can’t be a leader, no matter how good he might think he looks in pin stripes.

See also: Toby Manhire on the NZ election that could have come straight out of The Thick of It

Peak Cray: Making TV current affairs during NZ’s strangest election