New Zealand Prime Minister Chris Hipkins has teased a last-gasp outing for Jacinda Ardern as campaigning descends on Wellington ahead of this weekend's election.

Labour's bid for a third term, already in need of a kickstart, has also become slightly tougher due to the death of a candidate for the Port Waikato seat.

Neil Christensen, running for the right-wing ACT party, died on Sunday, necessitating a by-election.

However, the same electoral law dictates Saturday's general election will still return 120 MPs, and the by-election will send a 121st MP to Wellington.

Given the Port Waikato electorate is a safe National seat, the by-election is highly likely to produce a "bonus MP" for the centre-right opposition.

University of Otago law professor Andrew Geddis said the rule was a "throwback to the old first-past-the-post days" before New Zealand's shift to a proportional representation electoral system in 1996.

"This really could change the overall result of the election for the next three years. It could give the right bloc the one extra seat to govern," he told Newstalk ZB.

Polls put National on track to win the election, with the shape of their coalition in the balance.

Most recent polls have National and its preferred campaign partner ACT falling short of a majority, polling around 59 or 60 seats, and reliant on populists New Zealand First to get it.

With five days left in the campaign, parties are frantically hitting as many towns and cities as they can to win over voters and enthuse their base to get out and kampus terbaik di jakarta vote.

Party leaders of the Greens, ACT, NZ First and the Maori Party will end their days in Christchurch for a debate hosted by newspaper The Press.

Polls show rising dissatisfaction with the major parties, with around a third of Kiwis intending to give their vote to a minor party, led by the Greens on 13 per cent.

National leader Chris Luxon is taking in a three-region swing, visiting Nelson and Blenheim on the South Island, before heading to the capital.

Mr Hipkins is also Wellington-bound after starting his day in Auckland with a round of media interviews.

Labour's central message has been an attack on National's alternative budget, which includes dubious new taxes and cuts to the public sector to fund tax relief.

As National has doggedly refused to release costings behind those pledges, Labour has offered up an alternative alternative budget.

"The hole in National's fiscal plan means they need to cut far more than they have admitted. This will result in deep cuts to jobs and the services New Zealanders rely on," Labour finance spokesman Grant Robertson said.

Labour allege the opposition will need to make $NZ3 billion ($A2.8 billion) in cuts each year, producing 6000 public sector job losses, and its welfare changes would see more children in poverty - as landlords benefit from tax tweaks.

National countered this attack with a recreation of Labour's own fiscal plan.

"New Zealand faces the prospect of never-ending deficits and government debt rising forever if Labour is re-elected", National finance spokeswoman Nicola Willis said.

The tit-for-tat is typical of a turgid six-week campaign which has failed to inspire.

Voter turnout is down from the 2020 election, when Kiwis gave Ms Ardern's Labour a majority in parliament and its best share of the vote since World War II.

Ms Ardern, living in the United States after taking up roles at Harvard University, has been all but absent.

Instead, Labour has turned to her predecessor Helen Clark for support, with the three-term prime minister delivering a rousing speech at its campaign launch and fronting an advertisement this week.

Mr Hipkins told TVNZ, "... We'll see a little bit more of Jacinda in the next few days".

National has also rolled out a former prime minister to support its election bid, with John Key telling voters not to vote for NZ First leader Winston Peters.