Nicola Willis shows she is ready to fight her way back into power in November

Nicola Willis went straight after Labour and its election campaign costings over the weekend.

Photo: RNZ / Louis Dunham

Analysis: Nicola Willis is in combat mode ready to fight her way back into power in November.

The Finance Minister replaced one flak jacket for another on Sunday when she marched into her caucus room as National Party finance spokesperson and went after Labour and its election campaign costings.

Willis has operated this way for much of her time in the finance hotseat, but particularly this year as she has wrestled with criticism about her small Budget offerings and relentless determination to slash and cut to get to a point where a surplus can be reached sooner.

It is a reputation of fiscal responsibility and conservatism - an intentional contrast to what she says was a tax and bazooka gun spending approach by the last administration - that she has tied herself to since her first Budget.

But she took the offensive approach to new heights on the eve of Parliament's scrutiny week, calling reporters to a press conference to announce Labour had an $18.2 billion hidden bill it needs to explain.

She decided to stop short of joining her finance predecessor Steven Joyce who famously declared Labour had an $11.7 billion fiscal hole in the lead-up to the 2017 election.

Willis instead framed it as her giving Labour a chance to answer her questions, but if they had not by the election then she warned she would happily upgrade it to a fiscal hole.

Willis and her team say they have calculated the gap between Labour's spending plans and revenue intentions by pulling together policy announced so far, along with comittments made in the media to reverse or reinstate policies and programmes.

The accounting is based on some assumptions, though Willis was quick to point out that in the case of last week's public transport fare cap pledge she has been generous by believing their costings of $65 million a year, even though National has been clear they think it's too low.

On other policies she made assumptions that are far more extreme, such as in the case of the Future Fund, where Labour hasn't said which Crown owned companies it would transfer dividends from, but Willis decided to base it on the five biggest ones.

What Willis set out to achieve on Sunday was painting Labour as economically incompetent - a tactic played by every National Party since the beginning of time.

The risk for her is voters question why she's so bothered by Labour and its policies, when she could be spending time talking about her own.

It could be interpreted as National feeling threatened.

They would have reason to be, given the tight polling that has not really shifted the entire time they have been in government.

Willis' approach to the Budget last month was to not give sugar hits but instead remind New Zealanders that the country is in huge debt and the way out of it is to be fiscally restrained and feel a bit of pain now, to benefit in the long run.

That does not look to have resonated with New Zealanders, at least not in the first post-Budget poll released on Friday, that showed barely any movement at all from the Taxpayers' Union Curia poll a month earlier.

It still had the coalition government in power if an election was held today, but only just.

Then there is the Ipsos Issues Monitor Survey that has had National flailing in all the key metrics it traditionally thumps Labour on.

Concern about fuel prices soared to the fourth-biggest issue for New Zealanders in May, yet despite Willis' strong focus and competent handling of the issue, Labour was rated best able to tackle the problem.

Labour was rated higher than National on four of the top five issues - inflation/cost of living, healthcare/hospitals, petrol prices/fuel, and housing.

The only one National got a leg up on was the economy, which it had lost to Labour in November, before tying equal on the issue in March.

National will have been banging their head against a brickwall about how to claw back areas like the economy and inflation, which are the traditional stomping ground of the blue party.

Sunday's show of trying to make Labour look financially inept is politically savvy from Willis.

It forces Labour on to the backfoot in having to respond, and while some swing voters might see it as National playing politics in election year, there will be plenty who will hear the questions Willis is asking and agree it's time for some answers.

If, when in government, Labour had put together a document with these sorts of costings in June - still five months out from the election - and demanded National come clean, Willis would have been one of the first to say how ridiculous it was.

There is an argument that it is a very high threshold to be setting for an opposition that has far less resource and access to officials than a government of the day.

But that does not mean the costing questions, like what will pay for the policies they have already announced, where they're going to collect additional revenue from, and what other programmes and initiatives they're going to revive, are not valid.

If National is making a case for more of it in the future they will find plenty of supporters, but the same bar will be set for the party the next time it finds itself campagining from the opposition benches.

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