Ben Thomas: Jacinda Ardern, Bill English in game of chicken over Winston Peters

• Ben Thomas is a former National Government press secretary and a consultant with Exceltium, whose clients include the Act Party. These are his personal views.

This result of this election will turn on a tick. If septuagenarian New Zealand First leader Winston Peters improperly over-claimed his New Zealand superannuation by incorrectly filling out his application form, then what looks like a micro-scandal could grow to much larger proportions.

His initial claim that he was accidentally overpaid, like Metiria Turei's first admission of over-claiming an accommodation allowance, increasingly seems to not be the full story.

Peters needs to draw a line under this matter quickly by releasing his correspondence with the Ministry of Social Development, which he has suggested is brief and conclusive. The possibility that he improperly sought a level of benefits to which he was not entitled has to be dispelled immediately.

In any case, the longer this story drags on, the longer the public is reminded that the man campaigning on a "mood for change", the putative rock-star of the 2017 election campaign (before he was eclipsed by Jacinda-mania) is an old-age pensioner. If he did innocently fill out the form in error, advocates for beneficiaries and the elderly who argue that application forms are too complex for their clients would be vindicated, but it would not provide assurances about a future government featuring Peters.

The public will also be reminded that the politician who famously denounced the "baubles of office" continues to draw national superannuation despite being on a taxpayer-funded party leader's salary since late 2011, and presumably would continue to receive the weekly benefit if appointed a minister after the election. At a time when homeless families seek refuge in marae for the winter, this is not the look a fearless anti-establishment campaigner would want.

But this is not merely a problem for Peters. It is a dilemma for both National and Labour. Polls have shown since 2015 that New Zealand First is expected to be in a position to choose the next government. As one of National's current support parties, United Future, essentially collapsed into dust last week, Bill English accepted this and described the remainder of the campaign as a "drag race" against Labour.

The prize of course is a government with Winston Peters and New Zealand First. That's why to Ardern and English right now it probably feels less like a drag race and more and more like a high-stakes game of chicken. Winning may involve a headlong collision resulting in a messy coalition mired in controversy from day one.

It is a game that rewards nerves of steel. Both National and Labour have indulged Peters to date, vying for his favour, treating the overpayments as a matter of personal privacy we may never get to the bottom of.

After Peters failed to properly declare a six-figure donation towards his legal costs, John Key ruled out working with New Zealand First in 2008, a decision which helped to see the party dumped from Parliament and Key win government.

If Peters cannot clear this up quickly, National and Labour must judge how far they can distance themselves from him while still leaving open options for government. And part of that calculation is the wreckage of the other parties in this campaign: United Future is ready to be junked, the Greens have lost parts all over the road. Could New Zealand First be next?

Jacinda Ardern has already surprised supporters and critics with her steeliness as Labour's "smiling assassin", as she reluctantly and empathetically clambers over the bodies of previous deputies, leaders and memorandum of understanding partners towards the prime ministership. She stole a march on English by decisively saying Peters would not serve as PM or finance minister in a Labour government, while joking about their shared love of whisky and ribbing him like an old uncle.

In contrast, English will not rule "in or out" a finance portfolio for Peters. While leaving the door open further for Peters, he arguably needs New Zealand First less and risks looking indecisive.

Instead, English is kicking that can down the road until after the election, to see what voters decide. So either way, the election will be decided by a tick.