The Electoral Commission says a referendum on changing the New Zealand flag at this year's general election would be a major logistical exercise.
The Prime Minister on Wednesday raised the possibility of holding a referendum on a change, saying he prefers the silver fern, saying he would consult senior Cabinet ministers to decide whether to push ahead with a vote.
If there is a referendum, Mr Key said voters would be able to choose between the current flag or another option picked by the Government.
However, Electoral Commission spokesperson Anastasia Turnbull said it would be a major logistical exercise to have such a ballot ready in time.
The Governor-General says the time has come for at least a discussion about the flag's future. Lieutenant General Sir Jerry Mateparae says New Zealand has more in common with the Pacific than it does with the United Kingdom, and because of this the flag may now be outdated.
Silver fern not seen as best alternative
The head of the Returned and Services Association says the silver fern is not necessarily the best alternative for a new flag.
RSA president Don McIver told Radio New Zealand's Morning Report programme on Thursday most of the its members are against changing it, but if the move received widespread support they would want to be involved choosing the new design.
Mr McIver said is concerned that the silver fern can look like a white feather - a symbol of cowardice.
Branding expert Malcolm Mitchell from Massey University said changing the flag is a good idea - but a black and white design is the wrong way to go as a colourless flag may easily go unnoticed.