Prime Minister Jacinda Ardern has put herself directly at odds with Winston Peters on the future of a bill that would legalise voluntary euthanasia, saying she doesn't want it to go a referendum.

Act leader David Seymour's End of Life Choice Bill - which would allow terminally ill adults to request legally dying - passed its second reading in Parliament 70 votes to 50 last week.

MPs will now consider a swathe of potential changes to the legislation before it gets its third and final reading, the most significant of which may be whether to put the final decision to a public referendum.

While Labour and National MPs are voting individually, rather than along party lines, Deputy Prime Minister Peters' NZ First has backed the bill as a block - and only on the condition it eventually goes to a plebiscite.

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Ardern on Monday told reporters she didn't want it to go to the public.

"My view is that a referendum isn't required to ensure that the voice of New Zealanders has been heard and to reflect the will of Parliament and the people they represent," she said.

"I will be voting for the bill to continue as it stands."

NZ First leader Winston Peters has said it's a
NZ First leader Winston Peters has said it's a "referendum or nothing". Photo / Jason Walls

But she wouldn't rule out voting for a referendum if it was the only way to get the bill through.

"I acknowledge that's a second option," Ardern said.

Peters last week said it was "referendum or nothing" – although it's not clear yet whether his party would vote "no", abstain or let MPs vote individually if the referendum amendment doesn't get approved during the upcoming Committee of the Whole House.

"We want the public to have the decision on moral and ethical issues, not a few parliamentarians," he said.

Losing his party's nine votes would be a serious blow to the legislation's chances of getting into law.

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But neither NZ First nor Seymour are clear on whether they could muster the 61 votes needed to get the referendum added.

While Ardern was on Monday keen to point out she only had one vote and wouldn't be putting pressure on any other Labour MPs, she is not the first to come out against the amendment.

Labour's Louisa Wall, who has staunchly supported the bill, last week said was she would oppose holding a referendum because a public debate risked hurting already stigmatised and vulnerable people.

On the other end of the spectrum, National's Chris Penk said he was taking a cautious approach to the idea.

"It's more about whether a referendum is appropriate for deciding something where particularly minority rights are at stake," he said.

A number of MPs also gave their support at the second reading, but said their vote during a third would be contingent on whether enough safeguards were put in place when amendments were considered by the House.

Meanwhile, National's Maggie Barry - a firm opponent - has vowed to lodge about 120 amendments to the End of Life Choice Bill, potentially delaying a final vote by months, but denies she's filibustering.

The legislation will return to the House for debate at the end of this month.