Opponents of a bill legalising voluntary euthanasia say they're buoyed Parliament's support for the legislation has thinned at its second reading and are vowing to only get louder.

The End of Life Choice Bill, which in its current form would allow adults with less than six months to live or with a "grievous and irremediable medical condition" to request assisted dying, was passed 70 votes to 50 in a conscience vote by MPs on Wednesday.

At its first vote, in 2017, it passed 76 votes to 44.

The Select Committee that earlier considered the legislation received an unprecedented 39,000 submissions, 90 per cent opposed.


Anti-euthanasia group DefendNZ spokesman Henoch Kloosterboer said the opposition voice would keep growing.

"It's not going to change. It's not going to stop. There are so many more conversations to be had between now and third reading," he said.

"This thing isn't going away. The risks aren't going away. The burden of proof is on the proponents to prove vulnerable New Zealanders will not be placed at risk."

National's Maggie Barry says the size of the majority for the bill was
National's Maggie Barry says the size of the majority for the bill was "misleading". Photo / Mark Mitchell

A number of MPs, including Labour's Willie Jackson and National's Judith Collins, 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.

Lobby group Euthanasia-Free NZ also, despite the bill passing, said it was encouraged by the numbers and the issues raised by some MPs who voted for the bill.

"Several MPs who have voted for the bill this time expressed significant concerns," executive officer Renée Joubert said.

"We are doubtful the bill can be made safe."

National's MP Maggie Barry has been one of those staunchly against the legislation, said Wednesday's majority was misleading.


"They were swayed by the notion this would be a big opportunity to explore all the options. And some of my colleagues didn't want to leave it there. They wanted to explore whether this bill could be salvaged," she said.

She said a number of MPs who voted "yes" had told her they still had "grave doubts".

The bill's sponsor, Act leader David Seymour, accepts there's a battle to come.

"We're going to have to work really hard to persuade all of those people that the improvements at the committee stage will actually satisfy them," he said.

"But I do think it's possible."

The bill now goes to the Committee of the Whole House for debate and Seymour has promised to make changes to get it into law.

NZ First has so far supported the legislation on the condition the Act leader will amend it to require a referendum.

The Green Party's support at a final reading is conditional that the bill only applies to those with six months to live.

If the House can't agree to either of those conditions during the Committee of the Whole House, the legislation's future could become significantly less certain.

The bill will return to Parliament for debate at the end of next month.