National is considering a member's bill promoting the Kermadec Ocean Sanctuary - and potentially driving a wedge between two parties in the new government in the process.
A bill to create the sanctuary is already before Parliament, but it was put on the backburner last year amid legal objections from the Māori Fisheries Commission, Te Ohu Kaimoana.
While some media have reported the plan is already a casualty of Labour's coalition agreement with New Zealand First, outgoing environment minister Nick Smith said National would consider introducing a member's bill to get the sanctuary over the line.
The Green Party is adamant the sanctuary should be established, and, because National holds 56 seats in Parliament, only the Greens' support is needed to pass the legislation.
Dr Smith said the Greens would have to support the bill if it was drawn from the ballot, or risk alienating their support base.
"They introduced their own member's bill and so if National did introduce a member's bill, we could count on the Green Party's support and get this important sanctuary in place."
Should the bill be drawn it could place Labour in the awkward position of having its confidence and supply partners immediately voting in favour of a National Party bill.