More people would be in favour of legalising cannabis for recreational use if they were educated about it, the Drug Foundation says.
A Newshub-Reid Research Poll found 48 percent of people disagree with legalisation, while 41.7 percent agree.
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Executive director Ross Bell told Newshub people often go with their first instincts.
"I think we need to understand what that gut reaction is and start to talk to New Zealanders about 'well do you want cannabis controlled by the gangs or do you want a public health approach?'"
He said the current system of prohibition is not working and needs to be changed.
Bell said the Government needs to get involved in the education campaign as there's currently a lot of lies spreading about the drug.
"At the moment there is a vacuum and that vacuum is being filled by myth and misinformation and so the Government does actually have a responsibility to get facts and figures out there."
But he also says private citizens should get involved in the campaign too.
"If people support reform they need to start getting out there and talking to their friends, their family, their neighbours, their work colleagues about why the status quo isn't working and what we need to do to fix it."
New Zealanders will vote on whether to legalise the drug at the 2020 election. Draft legislation will include a minimum age of 20, regulations and commercial supply controls, limited home-growing options, and a public education programme.
The Newshub-Reid Research Poll found Green Party voters were most likely to say 'yes' to legalisation, while National were most likely to say 'no'.
The poll found that 76.9 percent of Green supporters were in favour, while just 14.5 percent opposed.
It's a stark contrast to just 25.3 percent of National supporters who want it legalised, while 67.6 percent were opposed.
The majority of Labour supporters want recreational cannabis legalised, with 50.4 percent in favour and 37.9 percent opposed.
That compares to 44.5 percent of New Zealand First supporters in favour, while 45.3 percent were opposed.