Voting papers for the Port Waikato electorate had to be reprinted after the original forms had no circle for voters to tick next to Vision New Zealand's name.
There was a space, but no circle, for voters to tick next to the party's name on the papers.
The mistake was discovered at around midday on Monday, after which voting continued using papers with the correct format, the Electoral Commission says.
But Hannah Tamaki says the formatting error left the party feeling insecure about the ballot papers around the country.
"When you consider the machinery of the Electoral Commission and the machinery of a new minor party, how is it possible that this has happened?" she said.
"How is this even possible, after all of our hard work, and the fact that we are
a fledgling minor party, first time out of the blocks, that this could even happen to us?
"Even more concerning is the fact that it includes an area where I am well known by family and close friends, and we've done a lot of work in this entire Port Waikato area," she said.
Vision New Zealand is currently polling at around 1 per cent, according to the latest 1 News Colmar Brunton poll, released last Monday.
Tamaki said around 1900 votes had already been cast in the electorate, which includes Pukekohe, Waiuku, Pokeno, Tuakau, Clarks Beach, Port Waikato, Mercer, and Maramarua, before the mistake was found.
Polls opened on Saturday and will be available for two weeks of voting until election day on October 17.
Advance voting has been increasingly popular in recent elections, accounting for 47 per cent of votes at the last election, and that is expected to rise to about 60 per cent this year, partly driven by the threat of another lockdown.
Tamaki said the news was a "massive disappointment" for the first-time party.
"Vision New Zealand has been in the spotlight from inception. It's disappointing that when you are trusting other people to do their job, they are letting the voting public down, and also disadvantaging us."
Tamaki said Vision New Zealand would continue to move forward "regardless of these hurdles continually thrown at us".
Additional ballot papers were being printed to ensure sufficient supplies were in place, the Electoral Commission said.