A crucial vote on whether to hold a referendum on legalising voluntary euthanasia looks set to go down to the wire, according to a poll of all MPs.
Act Leader David Seymour's End of Life Choice Bill will return to Parliament on Wednesday and politicians will have to decide whether the final decision should be put to the public if it passes a third reading.
If the referendum is rejected, the entire bill – which would let terminally-ill adults request assisted dying – will struggle to pass into law at the third vote, with New Zealand First looking like it may pull its support unless there's a referendum.
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The Herald has polled every MP in Parliament and found 56 now say they will vote for the legislation to go to a referendum or are leaning towards it.
That counts a number of MPs, including Prime Minister Jacinda Ardern and Finance Minister Grant Robertson, have who indicated they will only back a plebiscite it there's no other way to get the bill through.
There's 46 MPs who have said they'll oppose it or are leaning against it. It needs 61 votes in the House to pass. The decision will be as a conscience vote, meaning MPs will vote individually, rather than along party lines.
But there's 18 MPs who have not said how they're voting.
And 10 of those undeclared politicians voted for the End of Life Choice Bill at its second reading. It's likely at least five or six of them will back the referendum to ensure the bill can pass into law, like their colleagues.
Under that situation, the referendum will pass, but only narrowly.
It means even a few MPs changing their minds could swing the vote against a referendum. Some members were understood to still be changing sides on Tuesday.
There is, however, a number of MPs who oppose the bill – such as Labour's Deborah Russell – who say it's a close decision and feel more comfortable with putting the issue to a public.
The group could possibly be joined by one or two more who were "no" at the second reading, but still haven't declared how they'll vote on Wednesday.
The referendum failing would spell serious trouble for the legislation as a whole.
The bill passed its second reading 70 votes to 50, but the referendum has been demanded by NZ First, which says the issue is too serious to leave to politicians.
Several of the party's MPs have previously said all nine of the party's members will vote against the End of Life Choice Bill if the public aren't allowed to decide.
Leader Winston Peters wouldn't confirm this week whether NZ First members would be allowed to back to the bill without a referendum.
Without their votes, Seymour would have to retain every other "yes" vote from second reading into the third – a major ask, given a number of MPs publicly expressed reservations even while backing the bill last time.
Seymour has made a series of changes to the bill since the second vote in a hope of securing further votes, but it's not yet clear whether that's won him any more votes.
That's why the Act leader has been trying to rally support for the referendum for months now, even though it would slow his legislation.
And it's why the End of Life Choice's opponents may be more likely to vote against a referendum.
Publicly, a number have also raised the same concern as the bill's supporters – that the issue is simply too complex to leave to a yes-no referendum question.
Polling would also suggest a referendum would get the public's backing.
Victoria University research fellow Jessica Young, an expert on the issue of assisted dying, saying over the past 20 years public support for some form of assisted dying has averaged about 68 per cent.
Public campaigns surrounding the End of Life Choice Bill this year don't appear to have shifted the mood much either, with a 1 NEWS Colmar Brunton Poll in July – ahead of the second reading – saying about 72 per cent of the public supported assisted dying.
HOW THEY'LL VOTE:
*This list includes MPs who have indicated they'll only back the referendum if necessary to get the bill passed, and does not necessarily reflect their support for a referendum.