New Zealanders began voting on Thursday on whether to adopt a new flag, in a referendum Prime Minister John Key has called a once-in-a-generation chance to ditch Britain's Union Jack from the national banner.
After 18 months of heated debate, Kiwis must choose between an existing flag that Key insists is a colonial relic and an alternative silver fern design critics label "an ugly beach towel".
About three million ballot papers are being distributed in the South Pacific nation of 4.5 million people for the vote, conducted only by post, which closes on March 24.
The result will be binding and John Burrows, the head of a panel overseeing the referendum, said New Zealanders would have to live with their choice far into the future.
"Whatever the decision, this flag will fly for generations to come," he said.
Key said the vote was a rare chance to update and modernise a national symbol for the first time since independence from Britain.
"If they don't vote for change now, they won't get another chance until we become a republic," he told Radio New Zealand this week.
"I don't think that's going to happen in my lifetime."
On one side of the ballot is the existing flag, a dark blue ensign with the Union Jack in the top left corner and four red stars representing the Southern Cross constellation.
On the other is the proposed alternative -- a silver fern on a black-and-blue background, which retains the four Southern Cross stars.
Created by designer Kyle Lockwood, it beat four other flags in a preliminary referendum last December.
Opinion polls point to a decisive win for the existing banner, with a survey this week putting its support at 63 percent, against 26 percent for the new version.
Veterans' group the Returned and Services Association argues that to change the flag disrespects previous generations who fought and died under the banner.
"They have made the ultimate sacrifice for their country, it is to the flag we turn to honour their courage, commitment and sacrifice," it says on its website.
Others criticise the design's aesthetics, with actor Sam Neill saying, "This ugly beach towel is no alternative. It's hideous."
But there are high-profile advocates for change, including ex-All Black skipper Richie McCaw.
McCaw said he became convinced when he saw the almost-identical flags of Australia and New Zealand flying side-by-side as he ran out to contest the Rugby World Cup final in Twickenham last year.
"The silver fern has always been the special symbol on the All Black jersey... so the new flag with a silver fern as a part of it would be a great option," he posted on Facebook.
Key argues the silver fern "screams New Zealand" in the same way the maple leaf instantly identifies Canadians.
However, the conservative leader's strong personal support has fed perceptions the flag issue is his pet cause, hindering its chances of success, according to political commentators.
The New Zealand Herald's Audrey Young said the debate had been 'hijacked for party purposes' by those keen to strike a blow against Key, whose popularity ratings remain stubbornly high even after eight years in power.
The centre-left Labour Party, normally a reformist organisation, has condemned the NZ$26 million (US$17.3 million) referendum as Key's "hugely expensive and highly unpopular vanity project".
"It's simply a distraction at a time when so many more important issues are facing the country," Labour leader Andrew Little said.
Key said the flag issue had no bearing on his personal popularity and those trying to use it "to give me a bloody nose" were wasting an opportunity for reform.
"The crazy thing about it is that they'll wake up in a few months time and realise what a terrible mistake they've made because it's not going to make a blind bit of difference to me," he said.