Prime Minister Jacinda Ardern has announced the date of the Hamilton West by-election, which was triggered by the resignation of incumbent MP Gaurav Sharma.
Speaking to reporters in Auckland after meeting with the new Auckland mayor Wayne Brown, she said the by-election would be held on 10 December, with candidate nominations closing on 8 November - less than three weeks away.
She said she had overnight received advice on the potential timing from the Cabinet Office and the Electoral Commission.
"That advice gave me a limited number of possible options given the time of year that we're in - public holidays and so on - and of course needing to take into account the final tally of votes being delivered before we move into significant end-of-year events," Ardern said.
"I am still disappointed on behalf of taxpayers that we're having this by-election in the first place. It's been triggered by the fact the independent member for Hamilton West has decided to resign in order to run as an independent member for Hamilton West. That seems to me to be a complete waste of money."
The major parties have both played down their chances of winning the seat.
Ardern said Labour was going through its usual process ahead of the Hamilton West by-election.
"I don't think anyone thinks the scenario that Hamilton West has just gone through has been particularly edifying. I'm incredibly disappointed about what a Labour candidate has done so I'm sure that may well be an issue for us, but of course these are the circumstances we find ourselves in.
"We will stand proudly on our record as a government, and what we've been doing in the Hamilton region."
He was expelled from the caucus in August for breaching the party's code of conduct. It meant he was no longer a Labour MP and would remain in Parliament as an independent, but he was still a member of the party.
He resigned as an MP on Tuesday, saying he had heard from a credible source the party planned to use the waka-jumping legislation to remove him from Parliament in the six months before next year's general election.
Prime Minister and Labour Leader Jacinda Ardern, Party President Claire Szabó, and top-ranking ministers have all rejected his claims, saying there was no plan to use the waka-jumping law and Sharma was speculating.
Writ day will be Wednesday 2 November.