Winston Peters is a colossus of New Zealand politics, and his New Zealand First party is, once again, poised to be the lynchpin in this year’s election campaign. But so much hinges on whether his party makes it over the electoral system’s all-important 5% threshold.

Being the only centre party in parliament has made NZ First incredibly powerful. It can, and does, pivot between the left and right blocs of Labour-Greens and National-Act. Since 1996 when New Zealand adopted the mixed-member proportional electoral system, NZ First has decided the government three times – throwing its lot in with National once and Labour twice.

This willingness to work with either side is why it was able to set up an auction between Labour and National after the last election in 2017, to secure the best deal in exchange for letting one of them lead the government. Jacinda Ardern’s side won, resulting in Peters becoming deputy prime minister, and his party winning all sorts of policy prizes and ministerial positions.

In government, the party has wielded great influence, preventing Labour from progressing reforms NZ First deem too liberal or leftwing. A proposed capital gains tax was vetoed, climate change and employment policies watered down. However, their pursuit of populist policies has also assisted the government’s overall popularity in some ways – particularly in the regions where Labour is weak.

Winston Peters’ kingmaker role is likely to be reprised this year if – and it’s a big if – his party survives. Right now NZ First are facing the same sort of headwinds they did as a junior coalition partner with Labour back in 2008 – right down to the accompanying finance scandals and lack of electorate seat as a backstop. It makes for a highly-unpredictable election year and outcome. Over the last two years the party’s average poll rating has been 4%. Under New Zealand’s proportional representation system, NZ First needs to get 5% of the vote or win an electorate seat – which is far from guaranteed, even if it cuts an electorate deal with Labour.

In the last few months, the party has also weathered several scandals – particularly around whether they have broken electoral laws over political donations. Scandal is never far from NZ First, and this time could prove fatal to the party’s self-styled anti-corruption and populist reputation.

If NZ First is wiped out, there is a much greater chance of National winning the election. National and Act would potentially have enough seats in parliament, possibly assisted by a new party, to form a government. If NZ First comes in under the 5% threshold, the mechanics of MMP would mean National and Act would require less than 50% of the vote to become the government.

The National party would love to see NZ First out of parliament. One way of doing this, which National is rumoured to be contemplating, is to rule out working with NZ First after the next election. This would reduce the relevance of the minor party and NZ First’s centre-right voters would be less likely to support the party, knowing their vote could only help the re-election of a Labour-led government.

If NZ First are voted out, there is still a reasonable chance of a Labour-Green government being elected. Freed of the more centrist or moderate impulses of Peters, such an administration would likely have a stronger leftwing or radical agenda than the current Ardern-led one.

However, if Peters has shown anything over a career that has spanned 40 years, and seen triumphs, defeats and comebacks, it’s that you can never count him out. NZ First often campaigns very well in election year, and as a pragmatic conservative populist party is very adept at scratching the electoral itches that might help push the party above 5%. The usual targets are immigration, Māori separatism, law and order, foreign ownership and various injustices.

As an elder statesman of parliament, Peters is increasingly unwilling to go so hard with conservative populism. But his heir apparent, Shane Jones, has willingly taken up the role of rabble-rouser.

If this election turns into a “culture war”, with National attempting to accentuate polarising social issues as a way to wedge this government apart from centrist voters, Shane Jones is shaping up to take advantage. His self-styled “politically incorrect” stances and utterances, designed to provoke outrage and invoke the wrath of progressives, are straight out of the Peters playbook.

This week Jones has shown once again the power of provocation, when he referred to a Māori land rights leader as a “putiputi” (young flower), leading to condemnation for sexism and an open letter from 100 Māori leaders asking him to apologise. Although most New Zealanders might agree that Jones is out of line once again, there will be enough who will stand firmly with Jones. Expect more of this, as NZ First prepares to fight for its life.