Suddenly, it's all gone toxic at Auckland Council. It's sudden, because as Mayor Phil Goff says, only last month the councillors put on a remarkable show of unity to pass his 10-year budget. And just last week they adopted a new 30-year vision statement for the city with only four votes against.

At several meetings recently, councillors have brought their best speechmaking skills to the table and listened to each other with open-mindedness and respect. You'd have to say that's pretty healthy.

As for Goff, he usually enjoys the support of a broadly united centre on council, including several members of the National and Labour parties and some independents. He commonly wins about two-thirds or more of the votes.

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So why have nine of 19 councillors chosen this moment to create a crisis of confidence? Not a "vote of no confidence", mark, but a crisis nonetheless.

The trigger was the report into a new stadium Goff commissioned a year ago and did not show to councillors. It contains sensitive information on property leases, but the secrecy offended some councillors. It's true they have a right to know what's going on, but it's also true that Goff has a duty of care with confidential information. (After all, as the leaking of the discontented councillors' letter proves, at least one of them can't be trusted.)

The discontented nine are not a bloc. Some are on the firm left of the political spectrum, others on the firm right. Some have a political outlook very close to Goff's, but they just don't seem to like him. A few of them are ambitious politicians.

Who are they? Cathy Casey is a leftist councillor who votes on merit as she sees it, sometimes with the mayor and sometimes against him. There is no personal animosity. Indeed, she has publicly praised the mayor on several occasions.

But she was offended that councillors were kept in the dark about the stadium study and then, as she saw it, patronised when they complained.

It's different for Mike Lee, who is also firmly on the left. He routinely votes against the mayor, delivering elegant and angry warnings that the sky is about to fall. Sometimes, he seems almost consumed by personal antagonism to Goff.

Wayne Walker and John Watson are different again. They're on the left but their political views are much less coherent than Casey and Lee's. They're on a short fuse with Goff as well.

Sharon Stewart consistently opposes the mayor from the right. But as with Casey, it's not personal. She has largely voted in tandem with recently deceased councillor Dick Quax, promoting an Act Party perspective of holding down rates at all costs.

Stewart has claimed she feels "bullied" by Goff, which he strongly denies. It's hard to know what's gone on behind closed doors, but her example – that she was lobbied to vote for the regional fuel tax – is odd. Both Labour and National lobbied hard on that issue, and why not? It's politics.

Two more rightist councillors, Greg Sayers and Daniel Newman, appear to have political and personal motives. They oppose Goff's policies and both seem keen to position themselves as an opposition leader-in-waiting. Sayers may run for mayor next year.

Christine Fletcher is different again. She's a National Party liberal and theoretically part of the broad centre on council. Indeed, she commonly declares herself in favour of Goff's proposals. But then she will explain that for some procedural or technical reason she can't vote for them. Fletcher is not big on teamwork.

Which leaves Fa'anānā Efeso Collins. He's one of six members of the Labour Party on council, but he has drifted away from Goff and routinely votes against him now. That's odd. Collins may want to become the leading next-generation leftist voice on council, or one day head to Parliament, but to do either he will need to find a way to work with his Labour colleagues.

Why has this discontent spilled over now? The larger political picture is that the council and the new government have worked hard to address Auckland's problems together – and as the transport accord shows, their relationship has been fruitful.

Discord at council upsets that progress and strengthens political opposition to it. Some of the discontented councillors want that; others, for their own reasons, are along for the ride.

Or perhaps it's just that, despite all the serious issues facing Auckland, half our councillors believe their own egos are more important. Whatever the explanation, the council has a toxic culture problem and it's the mayor's job to be the adult in the room. He has to fix it.

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