Two MPs from opposing parties, National's Nikki Kaye and the Greens' Kevin Hague, have joined forces to develop a bill that would legalise adoption by gay couples.
The National Party's northern regional conference in Auckland at the weekend passed a remit in closed session supporting adoption by couples in a civil union.
The party's national conference in July is expected to debate a gay adoption remit, although such a matter would be a conscience vote in Parliament.
It is possible that the Government could pick up the work Ms Kaye and Mr Hague are doing on adoption and surrogacy laws as a Government measure, while making some of the controversial issues a conscience vote.
Prime Minister John Key told the Herald yesterday the passage of the remit reflected the changing face of the National Party.
"The party is modernising. You can see by the number of young people. It's ethnically a lot more diverse than in was. It's more representative of modern day New Zealand. It's a very positive and healthy thing."
Ms Kaye, the MP for Auckland Central, said she had worked for 18 months on the issue with Mr Hague, a West Coast gay MP.
She said many couples had fertility issues and more were considering surrogacy.
It made sense to consider adoption and surrogacy together, as they reflected the more modern arrangements New Zealanders were choosing to structure their families.
When the MPs started at looking at the Adoption Act 1955, they decided it would be best to approach it from a perspective in which the welfare of the child was paramount.
Ms Kaye, who also supports gay marriage, said the Young Nationals had promoted the gay adoption remit.
"But the approach I am taking would be that you focus on the welfare of the child and that's not about somebody's sexuality."
The two MPs are drafting legislation to amend the Care of Children Bill 2004 based on a previous Law Commission report that looked at guardianship and adoption.
The measure should be ready in a few months, Ms Kaye said, and would be a private member's bill in her name or Mr Hague's.
It was a complex piece of work and there would be about 40 policy decisions. Some would be controversial, including the age of adoption, adoption by same-sex couples, adoption by single people, Maori adoption practices and issues relating to surrogacy.
Labour list MP Jacinda Ardern has a bill in the private members' bill ballot that would require the Law Commission to rewrite the law to allow gay couples to adopt.