New Zealanders will decide whether they want to make cannabis use legal at the coming election - but the Prime Minister won't reveal her stance.

Jacinda Ardern says Labour doesn't have a position on the use of the drug - and says it wouldn't be right for her to give her view ahead of the vote.

Ardern says it's not her job to influence how people will vote.

She wants them to trust the material the Government's putting out on the referendum and make their decision on that.

National Party leader Judith Collins has urged Ardern to reveal her stance, saying that she will vote yes in the issue. 

However, a majority yes vote in next month's cannabis referendum would not necessarily lead to its personal use being legalised if National is in charge after the election.

Collins says if the majority of New Zealanders vote for the sale and use of cannabis on a recreational basis - she'll put a bill into Parliament which sets that out.

She says they'll then see how it goes through select committee and there'll be public submissions.

Collins says we could end up with a different piece of legislation.

Listen to Josie Pagani and Matthew Tukaki join Heather du Plessis-Allan on The Huddle to discuss this and the other issues of the day