The Automobile Association is pulling out of a multi-sector group which is working on suggestions such as how much Auckland motorists might pay in new transport charges.
The AA was part of the Consensus Building Group set up by Auckland mayor Len Brown, which last year proposed two options to plug a $12 billion funding gap for transport projects over the next 30 years.
The AA says Auckland Council itself and not the group should be doing a new round of work which is about start, aimed at figuring out how high any new charges might be.
The AA does not believe the CBG, which has 17 members, has the skills required to construct the financial models which the council would then put to public consultation early next year.
The CBG was set-up by Mr Brown to ensure a wide range of views were taken into account in exploring new sources of revenue for transport projects that couldn't be afforded by existing taxes and rates.
In July the group settled on two differing mix of charges for the council to consider. One involved larger increases to property rates and fuel taxes, with tolls on major new roads, and slightly higher public transport fares.
It's preferred option included charges for using certain roads, along with smaller increases to rates and taxes. Both options included more funding from the Government. Neither had exact costings.
That report was to have ended the CBG's work, but the mayor has decided it should reconvene to determine exactly what the mix of charges might be, before the council puts them out for consultation.
The AA says it is not withdrawing its support for the high-level options laid out in last year's report. Spokesman Barney Irvine says the organisation wants to be able to represent the views of its members, as any new taxes and charges take shape.
"The devil is in the detail and that's the point of the debate we're getting to now", he says. "We're getting to the sharp end, and our sense is that it should be the council leading and taking ownership of that."
Peter Winder who is the project director of the Consensus Building Group, says it is disappointing the AA won't be taking part, but there is still a broad range of sectors involved. He doesn't think the next round of work will be compromised by the AA's absence.
"We're quite confident that it will still be a very meaningful product and that it will be something that the council can have great confidence in, in terms of picking it up and proceeding to consult the people of Auckland," said Mr Winder.
The AA's withdrawal is not a good look for what will be one of the most contentious pieces of work being led this year by the mayor Len Brown. He wants to put detailed proposals of what new charges might look like, to the public early in 2015.
Mr Brown would not comment on the AA's decision, but is understood to be disappointed.
Radio New Zealand's Auckland Correspondent Todd Niall says despite the AA putting its reasoning in a letter to the council, it is not completely clear why it has become wary about staying close to the CBG.
The AA's previous representative on the CBG, Simon Lambourne, left the organisation last year.
The letter also hints at internal politics within the AA playing a part. It refers to the risk of any further involvement with the CBG, being at odds with the organisation's national council which is yet to finalise a policy on infrastructure funding.
The CBG reconvenes next Monday with 15 members. It has also lost the representative from the parking company Tournament, due to workload.