The poll, conducted by TV3, revealed that as many as 70 per cent of New Zealanders are not in favour of changing the country’s current flag.
The flag change proposal will be put to a vote later this year, and Key believes there is still time to win the public over.
“It’s always going to be a tough ask to change the flag by a public referendum,” he told Radio New Zealand.
“You’ve got to engage people, you’ve got to get them to think through the issues… no one’s arguing it’s not a big challenge.”
A government committee recently unveiled four prospective designs for a new flag, three of which feature the image of a fern, which has long been used on the uniform of New Zealand athletes competing on the international stage.
Kiwis are being asked to pick their favourite in the upcoming referendum. The winner will then go head-to-head against the existing flag in a second vote in March of next year.
Key and his conservative government are keen to change the current design, which bears a striking similarity to Australia’s flag and features Britain’s Union Jack in the corner.
“Every audience I go to at the moment I ask them the question at some point and I haven’t had an audience that’s been more than 50 percent wanting to keep the flag,” said Key.
“In fact, the vast, overwhelming bulk want a change.”