Bill English and Jacinda Ardern spar in first TVNZ leaders debate as Labour surges to front in poll

National's slide in the latest 1 NEW Colmar Brunton poll, taxes, housing, polluted rivers, and global threats were thrashed out between National leader Bill English and Labour leader Jacinda Ardern in tonight's first TVNZ leaders debate of the election campaign.

Labour surged up in the latest Colmar Brunton Poll, but Jacinda Ardern isn't taking the numbers for granted. Source: 1 NEWS

It came an hour after the poll showed Labour up six points at 43 per cent and ahead of National for the first time in 12 years, while National has slipped three points to 41 per cent, its lowest level since 2005.

Moderator Mike Hosking kicked off the debate, asking Mr English why he's losing, to which the National leader shot back "We're not".

"We're focusing on rolling out our plans for the next three years. Very pleased with the positive response we're getting. We're a party that has shown we can deliver on all sorts of things from changing the lives of our children to building infrastructure," he said.

Mr English said National is seeing its numbers "a bit stronger than that" and said "the point is the voters are now looking to make in what's clearly a close election, a drag race between the two major parties".

Ms Ardern said she's "certainly not going decide it's somehow a done deal right now".

"There's been a huge amount of change in the last three to four weeks and yes, that's been in Labour's favour. But it can turn in either direction so I'm not taking anything for granted. I'm certainly taking those numbers with caution and we're going to keep working hard."

Mr English says Kiwis can have social and environmental objectives, but also tax breaks. Source: 1 NEWS

Mr English accused Labour of "vague high level statements" but Ms Ardern insisted Labour has a "fully costed, detailed fiscal plan."

She said Labour decided this is not a time for tax cuts but is focusing on health and education, partly from cancelling tax cuts, saying "I refuse to stand by while children are sleeping in cars".

Mr English asked if she could look meatworkers in eye and tell them she's "going to take $1,000 off them to make tertiary education a bit cheaper for lawyers" and said transparency requires she say how much water tax and other new taxes will be.

Ms Ardern said she is being transparent and has been "upfront with New Zealanders and told I them don't accept where we are with housing".

Ms Ardern hit back after Mr English said "every person without children will be worse off under Labour". Source: 1 NEWS

"People can't go shopping with your values," Mr English hit back. He said he announced at the Auckland City Mission today "we're going to end rough sleeping".

On immigration, Ms Ardern said Labour would reduce the current 70,000 migrants a year by around 20,000 to 30,000, a lot of them from "low value courses".

But Mr English said if the numbers coming here to do jobs changes it'll slow the economy down and houses won't get built.

Ms Ardern said lot of migrants are coming to Auckland, rather than the regions.  

Ardern signalled Labour will cut immigration by up to 30,000 people. Source: 1 NEWS

"We owe them a duty of care. If we're offering them the Kiwi dream we've got make sure we can deliver that."

To a viewer question about cleaning up rivers and lakes, Ms Ardern said a water royalty from water bottlers will support that and we have to "start walking the talk" on our clean, green image to "restore our brand".

Mr English says Kiwis can have social and environmental objectives, but also tax breaks. Source: 1 NEWS

Mr English said New Zealand is "smart enough" to be able to be high quality food producers for the world and high water standards and "it's not a trade off".

On the world scene, Mr English said he sure hopes the US "know what they're doing around North Korea because that is the biggest threat we face at the moment. I'm concerned that it's escalating to a point where mis-judgement could take us rapidly somewhere dangerous".

Having recently sent three more non-combat troops to Afghanistan Mr English said "we would have a pretty tough test for any combat involvement" if requested to participate in anything the US is doing but would consider that on its merits.

The controversial tax will also hit some dairy farmers and wine makers, as well as water bottlers. Source: 1 NEWS

Bill English and Jacinda Ardern were put on the spot over their policies on the drug. Source: 1 NEWS

Ms Ardern said she agreed with the deployment of three non combat troops to Afghanistan in the last month "but we're looking at a new mandate in June 2018 and at that point as prime minister I would want to review all of the information that currently I'm not privy to in opposition. I think you could call me very hesitant."