Wellington city councillors have unanimously agreed to submit a super-merger proposal to the government this weekend.

Councillors expressed "preference" that Wairarapa be excluded, and for the Hutt Valley, Porirua, and Wellington City to merge. However, they ultimately voted to support a wider regional proposal if mayors agreed on that.

Regional mayors will decide on Friday on the exact model - which could see a Wellington-Wairarapa unitary council - merging 8 councils together.

A layer of community councils could represent the Hutt Valley, Wairarapa, Porirua, Wellington City and Kāpiti.

In an hours-long debate, Councillors discussed whether they should force Upper Hutt into a merged council, whether Wairarapa should be included, or if a referendum should be put to residents.

In the Wellington-Wairarapa region there are currently eight territorial authorities and one regional council. There are 106 elected members, 12 community boards, and 55 community board members in the region.

Councils divided as deadline looms

The backdrop of discussions was fraught before the meeting on Thursday, with councils across the region disagreeing on the model as the deadline for the proposal looms.

Porirua and Lower Hutt city councils, along with South Wairarapa, agreed on a Wellington-Wairarapa council, but Upper Hutt City Council wanted to remain separate.

Masterton and Carterton want to create their own Wairarapa Unitary council, while Kāpiti wanted to remain either its own council or join with Horowhenua.

Mayor Andrew Little said the proposal being considered was "far from perfect", but it was the best the council could do given the rushed timeframe.

The decision was about future generations, he said. Wellington region had been "anemic" economically for some time, and was woefully under-prepared for climate change, he added.

It needed a bigger platform to advocate for itself, he said.

"Put aside Head Start, put aside the dodgy process, can we seriously address those challenges under the status quo?" My view is not."

Councillor Diane Calvert put forward an amendment signalling that councillors wanted four Wellington metro councils to merge, with Wairarapa excluded and forming its own council instead.

She said a survey of Wellington city residents had shown a majority did not want to join with Wairarapa.

Councillor Tony Randle agreed.

He said the Greater Wellington Regional Council was spending $30 million a year more in Wairarapa than it received in revenue from the area - and Wellington city ratepayers were subsidising services.

"What's been missing from this whole thing is the justification, of why Wellington city residents should be funding people who choose to not live in Wellington, but who actually live in far cheaper housing, far far away, and who pay much lower rates."

Little disagreed, arguing that Wairarapa and Wellington were "wholly integrated regions - not just 'rural folks' versus 'urban folks'".

He said excluding Wairarapa would increase transport costs for those residents and have a direct effect on the labour market.

Environmental regulations and management, currently carried out through the regional council, would suffer - to the detriment of the region.

Councillor Jonny Osbourne put forward an amendment - which passed - to seek advice from officials on a possible referendum later on the issue later in the year. It was indicated that central government would not support that.

Porirua and Lower Hutt had already done this, he said.

"If Wellingtonians are not given the same opportunity via a referendum, lingering discord with any significant reform with the way we govern ourselves will exacerbate divisions which naturally occur in communities, but are occurring unfortunately more and more."

That passed, with councillors discussing whether the process had been democratic at all.

What about Upper Hutt?

Councillor Geordie Rogers submitted an amendment that other councils shouldn't be coerced into a merger councillors had voted against.

The comments came after Upper Hutt City Council voted against any amalgamation plans, and mayor Peri Zee said that the city shouldn't be forced into a merger against its will.

Rogers said he was doing this in the interests of Wellington city residents, saying the disagreements between councils could lead to "bad consequences".

The amendment, however, failed.

Randle conceded four councils didn't want the plan, likening the arrangement to a "shotgun marriage".

"I don't think those marriages really work out," Randle added.

But he ultimately decided not to support the amendment, on the basis that Upper Hutt was part of the region's catchment areas and economy.

What do iwi representatives think?

Kara Puketapu-Dentice presented a letter on behalf of iwi leaders across the region, which urged councillors to think of future generations.

This was not a "restructure of councils", he said, but a chance to build something new.

"The decisions in front of us are mokopuna decisions.

"The people who will live longest inside what we choose are not yet in any of our rooms, and they will not ask which council held which preference in 2026," the letter said.

Councillor Matthew Reweti, representing the Māori Ward, said the Local Government Act and the Head Start process required discussions with iwi.

He said any future model must retain Māori representation.

In Wellington, 68 percent voted to retain the Māori ward, and Porirua, Lower Hutt, Kāpiti, Masterton and South Wairarapa also voted to retain the wards, Reweti said.

"The iwi leaders have come together...and they have asked councils to pursue the Head Start pathway, rather than default to the government's back stop process."

[h] What happens now?

On Friday, mayors will meet to work out the proposal which will go to ministers.

Speaking after the meeting, Little said he was confident an agreement on an amalgamation model could be reached.

"All but one council have all agreed they want to put forward a Head Start proposal."