Watch: A Newshub-Reid Research Poll has revealed most Kiwis don't think recreational cannabis should be legalised.

Watch: A Newshub-Reid Research Poll has revealed most Kiwis don't think recreational cannabis should be legalised. Credit: Image - Getty, Video - Newshub.

Previous polls by Horizon over the past 12 months have shown support falling from 60 percent in November 2018 to just 39 percent in August 2019 . But the new November 2019 poll shows an increase to 48 percent.

New Zealanders will vote on whether to legalise the drug in a referendum run with the 2020 election.

A new poll shows support for legalising personal cannabis use has risen by 9 percent in the past three months.

Cannabis vote: Why the Government decided on legal age of 20

"Back in August, it seemed the referendum was heading for defeat. I'm not so sure now," says Helius Therapeutics co-CEO Paul Manning, whose company commissioned the poll.

"A lot of support from middle-aged Kiwis has returned, with Labour and Greens' voters also now clearly swinging in behind.

"The reality is, who turns out on election day will ultimately decide the referendum result. Whether younger Kiwis will vote in higher numbers than in the past, remains a big unknown."

It's also unknown why support has increased in favour of legalisation.

"The result shows a definite lift in public support following a slump over winter, and there'll be plenty of speculation as to why," Manning says.

"Factors could include September's release of the Helen Clark Foundation's report titled 'The case for YES', the hit documentary series Patrick Gower: On Weed, and perhaps a reduction in scaremongering by conservative groups, for now."

The number of Green Party voters in favour has bouncing back from 64 percent in August to 73 percent this month. Labour Party supporters in favour have also notably risen, from 46 percent in August to 60 percent.

At the same time nearly two-thirds of National Party supporters remain against legalising cannabis for personal use. In August 64 percent of National voters were against, now lifting slightly to 65 percent. Overall, those against legalisation fell from 47 percent in August to 38 percent.

"The issue is now being driven by party voting allegiances: it's increasingly a partisan battle," Manning says.

Horizon polled 1199 people between 11 to 17 November 2019 intended to represent the adult population. At a 95 percent confidence level, the maximum margin of error is ±3.1 percent.