The most popular members of the royal family - including their newest addition - look set to visit New Zealand next year, even though it's an election year.

Plans are afoot for a visit by Prince William, wife Catherine and son Prince George - understood to be one of several events that the government will have to work around when setting an election date.

New Zealand Prime Minister John Key says there's no reason why the royals can't visit during election year.

"If they come in the election period - it's generally seen as that period where sort of three months beforehand - then there are all sorts of rules that apply there," he told TVNZ's Breakfast program.

That suggests any visit would be in the first half or last months of 2014, with the election likely to take place between September and November.

Mr Key says even if the royals did visit close to an election, he doesn't expect to gain much political capital from photo opportunities.

"I think it's a wonderful thing that they come and I'm a massive supporter of the royal family but I don't think someone goes into a polling booth and says `I'm going to vote National because Prince William turned up in New Zealand'."

The government was under pressure in 2011 to turn the royals away from the Rugby World Cup in New Zealand, as it fell close to election day.

A spokeswoman for Mr Key said at the time that any visit would be "private" to prevent it becoming "part of the pre-election political debate".

In the end, the royals didn't visit.

Mr Key has already met Prince George, who was born on July 22, when he and his family visited Balmoral - the Queen's estate in Scotland - in September.