On the eve of the flag referendum, Prime Minister John Key says his message to voters is it's a once-in-a-lifetime opportunity.
"It will probably never happen again in the lifetime of most New Zealanders who will vote in this referendum," he told reporters on Wednesday.
The referendum runs from March 3 to March 24, and ballot papers will be in the mail on Thursday.
Mr Key, wearing the alternative silver fern design on his lapel, said he wouldn't take the result personally.
"Not in the slightest ... I think it's been a pretty healthy debate about New Zealand and our nationhood, and I hope people will vote for the right reasons - if they vote because they don't like me, they will be wasting their vote."
Opinion polls are showing more than 60 per cent of voters do not want to change the flag, but Mr Key says he is hopeful.
"We are seeing the number of people who definitely want to keep the existing flag continuing to drop, but there is such a big factor in there of the undecided, and those things, and it depends on how many people turn out."
Mr Key said he had been disappointed by Labour's stance.
The party proposed a flag change referendum in its 2014 election manifesto, but opposes the one that starts on Thursday.
"When we did this it was based on the view that it was their policy," he said.
"They used politics, yeah, well people will judge that for themselves."
