The Green Party may have to support the waka-jumping bill into law because the party did not raise it as an issue during coalition negotiations.
The bill, which would ensure Parliament's proportionality in the event that an MP leaves or is ejected from a party, is part of the Labour-NZ First coalition agreement - but needs the support of the Green Party to pass into law.
Supporting the bill at its first reading has been the source of internal conflict within the Greens, leading former MPs Sue Bradford and Keith Locke to publicly criticise the party, with Bradford calling it dishonourable.
The Greens have vehemently opposed similar legislation in the past, and co-leader James Shaw has sought to appease the membership by saying that the party's ongoing support for the bill is not guaranteed.
Co-leader contender Julie Anne Genter has also talked up the possibility of opposing the bill in the future as part of her co-leadership pitch to carve an independent voice for the party.
But Young Greens co-convenor Max Tweedie, in a Facebook post last week following a call with the party executive that was screen-shot and posted to reddit, said that the party had no choice but to support the bill.
"James [Shaw] has explained why the Greens are supporting the waka-jumping bill," Tweedie wrote.
"NZF and Labour, and the Greens and Labour, conducted blind negotiations for the agreement. Labour requested a list of NZF policies that we don't support, and while we went through, we didn't even think of the waka-jumping bill.
"As a result, because of the agreements between us, we have to support the bill because our opposition wasn't flagged."
A spokesperson for the Greens confirmed that the party did not raise it as an issue during coalition talks with Labour because NZ First had not campaigned on it.
"We looked at the policies that parties ran on during the 2017 campaign. Waka-jumping wasn't one of them. We are now managing this issue within the Green Party."
The spokesperson would not say whether the party had to support the bill beyond the select committee, where the Greens hope the bill will be improved.
Tweedie added that while most of the Young Greens oppose the bill, it was not worth publicly opposing it because it would waste "political capital on something we can't change".
The Greens may be bound to support the bill because of a provision in its confidence and supply agreement with Labour, which states that the Greens will "act in good faith to allow" Labour to comply with its agreement with NZ First.
The Labour and NZ First coalition agreement says that a waka-jumping bill will not only be introduced, but passed into law.
The bill has been a thorn in the side of the Green Party since last December, when it was revealed that the caucus was considering asking for policy concessions in exchange for supporting the bill.
The idea was quickly dumped after Labour and NZ First both criticised it.
The Greens have said that the safeguards in the bill are sufficient for the party to support it to select committee.
Attorney-General David Parker has said the bill is consistent with the Bill of Rights Act, despite reservations that it would have a "chilling effect" on an MP's right to freedom of expression and freedom of association.