Just 12 days ago New Zealand's political landscape appeared settled in a shape that would more or less remain until the election.

With the startling departures of two party leaders, and the electrifying rise of a third, the outlook is suddenly unpredictable.

New Zealand politics have been rocked by these events. The outcome of the election, six weeks from today, has become a lot less certain. As a result, the campaign itself could become a whole lot more absorbing.

If more New Zealanders become engaged in determining who gets elected, there will be a democratic dividend.

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The ascension of Jacinda Ardern to the Labour leadership has dramatically lifted her party's support, clawing back voters who had left for the Greens and New Zealand First. In the preferred prime minister stakes, she is barely a percentage point behind Bill English.

The Prime Minister's National Party remains relatively stable in its share of support but must be concerned whether it can hold on to the backing of female voters over the course of the campaign. The direction that younger women voters head with Ardern as Labour leader will be exercising National's campaign managers.

At the end of a disastrous week for the Green Party - and a competent show by Labour - it is clear that Ardern has built momentum. She is the first Labour leader since Helen Clark who seems to resonate with the electorate as a potential prime minister.

The Government will not want to allow her any more wind at her back and is pointing to a sense of chaos on the left. But with Metiria Turei having finally fallen on her sword, the Greens may yet have enough time to create a semblance of order.

National remains far and away the most popular party with around 45 per cent support. This however is shy of the 47 per cent it needs to govern with its small partners, United Future, Act and the Maori Party.

Despite NZ First losing ground in the latest polls, the arithmetic reinforces the prospect of Winston Peters as kingmaker, or queenmaker in the case of Labour. Peters scoffs at polls showing his party losing ground and surveys in the past have underestimated NZ First support.

The difference this time is that Labour, with Ardern at the helm, is galvanised and gunning for office. An incumbent National Party without the immense electoral asset of John Key could find itself hurt, after nine years in charge, by a nascent mood for change.

Peters will still be a pivotal figure come election day, but the run of political tremors has created an opportunity to hear some clear-eyed ideas from those wanting to be elected.

With the unpleasant row about Turei's welfare disclosure parked up, is it now too much to hope that the country could expect some searching discussion about the issues?

Why not debate the fairness of existing welfare arrangements, ways to address poverty and the treatment of beneficiaries as the Greens and Turei had wanted? Why not thrash out a sensible water policy, which addresses Maori claims to ownership? Why not search for solutions standing in the way of affordable housing? Why not promote more ideas to get Auckland moving past its worsening gridlock without saddling the economy with debt?

These may not be front and centre concerns like the election staples of education, health and economic management but they are on the radar of voters. With the election wide open, let's have some talk that matters.