The outcome of the cannabis referendum is looking likely to come down to whichever camp can get most of their supporters to the polls.
The problem for the pro-legalisation camp is that their biggest supporters - younger voters - are less likely to bother.
The latest Horizon polling on the referendum found 46 percent in favour and 42 against - not dissimilar to another poll released on Tuesday, which had the 'yes' camp ahead 49-45. When those who said 'not sure' were forced to take a side, 52 percent overall said they'd vote 'yes'.
"The 'yes' vote has firmed up slightly, but it's still looking very close, with public opinion set to keep shifting right up until voting closes," said Paul Manning, chief executive of biotechnology company Helius Therapeutics.
Helius has commissioned regular polling on support for the legalisation of recreational cannabis for two years now. Support was initially 60 percent but fell to below 40 percent last year. It's since come back, with recent polling placing it in a dead-heat with continued prohibition.
"The quality of debate and the strength of arguments for or against legalisation in the next two weeks are now critical," said Manning.
"Turn-out of 18- to 34-year-olds will also be key. Young adults are the strongest supporters of the bill, but they also have the lowest registration and intention to vote."
Support for legalisation is strongest among those aged 25-34 at 69 percent. At the 2017 election, 25- to 29-year-olds had the lowest turnout amongst registered voters at just 67.6 percent. Those between 20 and 34 didn't fare much better, with just 70.9 percent turnout.
The country's youngest voters - aged between 18 and 24 - are also overwhelmingly voting yes (63 percent), but also had low turnout in 2017, at just 69.2 percent.
In contrast, the voters most likely to vote no - those aged 75 and over - are among those most likely to vote. The country's most reliable voters - those aged between 65 and 69 - are also mostly voting no.
Youth vote crucial
If only people under 55 voted, the referendum would pass easily. Perhaps too if it was taken on Twitter - new research finding 62 percent of all Kiwi tweets about cannabis are positive in nature.
Research published Wednesday in journal Drug and Alcohol Review found more than 300,000 tweets about cannabis written by Kiwis between 2009 and August 2020. Support appears to be growing, with 65 percent this year positive about the drug.
"Similarly, for referendum-specific tweets, the 2020 data reveal a generally positive view of cannabis," the study said - 53.5 percent to be exact - also noting that Twitter users are "more likely to be younger, earn more money and be more educated than the general population". Only 12.6 percent of tweets in 2020 on the referendum have been opposed to legalisation.
Voters split along party lines
Labour leader Jacinda Ardern has been repeatedly criticised for not revealing how she will vote in the referendum. National leader Judith Collins said on The AM Show on Wednesday she "obviously voted for it... otherwise she'd be able to say she didn't".
"I think she's reluctant because I think she also is very aware there is quite a majority of people who do not agree with the legalisation and sale of recreational cannabis."
Green Party voters were predictably 97 percent in favour, followed by Labour voters (65), ACT (42), NZ First (36) and National (22).
In terms of ethnicity, support was highest among Māori at 64 percent. Indian, Pasifika and NZ European voters are also in favour of legalisation. The only ethnic group named in the poll opposed to legalisation was Asian.
The poll was conducted online, with the 1481 respondents' answers weighted by age, gender, highest education, personal income, employment status and party vote. It has a margin of error of ±2.6 percent.