New Zealand First has thrown a wrench in the works of the abortion debate, suggesting its MPs' support for reform may depend on a binding referendum.
The 11th-hour revelation caught Justice Minister Andrew Little off guard at Parliament on Tuesday afternoon.
Mr Little yesterday unveiled legislation which would make it easier for women to access abortions and remove the procedure from the Crimes Act.
The bill - which will have its first reading on Thursday - was formulated after months of negotiation with NZ First.
But speaking to reporters on Tuesday, NZ First leader Winston Peters said his party's position on the legislation was still an "ongoing discussion".
"This was not in our manifesto at the last election. It's not part of our coalition agreement in any way, shape or form."
And, in a major shift, Mr Peters raised the prospect of there being a public vote on the matter.
"Referendums are what New Zealand First has stood for for a long time when it comes to conscience issues.
"Everybody that's been dealing with us knows that."
NZ First MP Clayton Mitchell made similar comments on his way into Parliament on this afternoon.
"We're working through it. It's something New Zealand First believes should probably be a binding referendum issue."
The comments are at odds with a recent interview given by his senior MP Tracey Martin who was tasked with negotiating the legislation with Mr Little.
On Monday night, Ms Martin told RNZ the party had no plans to call for a referendum and nobody in the caucus had raised the possibility.
But on Tuesday, Ms Martin declined to answer further questions on the subject.
"I've made the comments on the record ... and I don't have any further to make right this minute."
Stopped on his way into Parliament, Mr Little appeared angered at the last-minute news.
"It's never been raised with me in the months of discussion we've had," Mr Little said.
Mr Little said he did not favour the idea of a public vote on the matter.
"The situation with abortion is different from, for example, cannabis. We already have abortions - we have 13,200 of them a year - so all we're doing is changing the status of it."
Right now, a woman can only access an abortion if two doctors agree a pregnancy would put her at physical or mental risk.
The proposed law change would remove that requirement for women within the first 20 weeks of gestation.