We are in a period of great political volatility – the New Zealand election is far from decided | Bryce Edwards | Opinion

According to the Colmar Brunton poll published by TVNZ on Thursday, Labour would easily romp back into power at the upcoming election. Labour’s 50% support is well above the 37% support it won at the 2017 election, which was enough for Labour to form a coalition government with the Greens and Winston Peters’ New Zealand First.

On current polling, Labour could also form a government without the need for coalition partners – which would make it the first party to do so since 1993. Since New Zealand shifted to the MMP proportional representation electoral system, parties have required around 47% of the vote to form an administration, and no party has yet been able to do that alone.

In addition, Labour would also have the support of the Greens who, according to this poll, are on 6% – above the crucial 5% MMP threshold that minor parties who do not hold an electorate seat require to make it into parliament.

Labour’s current coalition partner, New Zealand First, is polling well below that crucial threshold, with only 2% support. Unless one of the party’s MPs wins an electorate seat – such as Shane Jones prising the Northland seat off National – then the party will be out of parliament.

The demise of this centre party might well be celebrated by Labour and the Greens, both of whom are increasingly finding NZ First to be a frustrating handbrake on attempts to implement progressive reforms.

While the latest poll is good news for the political left, the parties of the right have fared much worse. National is on 38% and Act 3%. It appears that the difference between the two ideological blocs – 15% – is far too wide to cause a change of government on 19 September. And if you look at the results for who the public prefers as prime minister, Jacinda Ardern is preferred by 54% of the electorate, while National’s new leader has only 13% support.

Yet the above reading of the latest poll is far too static. Once you consider polling trends over a longer period of time, and look at other polls, then you see great flux and volatility, and much less certainty that Labour will be re-elected.

In fact, the gap between the left and right blocs is closing quickly, according to Colmar Brunton. Labour suffered a massive 9-point drop in this poll, and Ardern’s popularity fell by the same amount.

Partly this is because the previous poll rewarded the incumbents with stratospherically high support, which was always likely to fall away. But the loss of support also reflects that the government has been hit by two weeks of damaging revelations about lax quarantine and border measures, which critics argue threaten New Zealand’s progress eliminating Covid-19.

Labour’s loss is the right’s gain – with National jumping up 9 percentage points, to 38%. Suddenly, what was a massive 30-point lead by Labour over National has dropped away to only 12 points.

National’s improved support can be partly attributed to the party’s new leader – with the widely-disliked Simon Bridges being replaced by Todd Muller. It might not warrant a #Mullermentum hashtag, but this improved polling shows that voters are now willing to listen to what he has to say.

National’s only solid potential coalition partner, the rightwing Act party, is also up in the latest poll to 3% – its highest rating in nine years. Because Act leader David Seymour will win his Epsom seat, the party would bring in three extra list MPs.

This buoyancy adds to the chances of National now being a competitive player in the election, threatening the left’s assumed hold on power. If anything like the trend continues in this poll for Labour and National, then both parties will soon be polling somewhere in the 40% range. Once, again the performances of the minor parties will therefore be critical as, in all likelihood, both Labour and National will require their support to form a government.

Beyond the Act party, it’s not yet clear which other minor parties will survive the very volatile political climate of the moment. Even the Greens can’t be certain of survival, given their relative invisibility of late, and a number of polls putting them close to the crucial 5% threshold. The Colmar Brunton poll records them at 6%, but the previous one had them at only 4.7%, and the most recent UMR poll two weeks ago put them on 4%. Furthermore, the party normally performs worse in elections than their polling suggests.

Meanwhile the Māori party is currently out of parliament, and records only 1% in this poll, but has just launched its comeback election campaign. They have a decent chance of winning one of the dedicated Māori electorates, Te Tai Hauāuru, in which co-leader Debbie Ngarewa-Packer has been assiduously campaigning over the past year. Such a win could further complicate post-election horse-trading – the Māori party has both ruled out working with National, labelling their leader as “racist”, but conceded if the deal was big enough they might consider helping them into power.

Thursday’s poll – which is just the latest illustrating public support is bouncing around – signals we’re in a period of great volatility and, although Labour is clearly in pole position, the election is far from decided. The left and right still have everything to play for.

• Bryce Edwards is a senior associate at the Institute for Governance and Policy Studies at Victoria University, Wellington, New Zealand