The Labour Party cannot rely on Auckland Council to pay half of the cost of its light rail proposal for Auckland, with mayor Phil Goff questioning whether the council should have to pay anything.
Party leader Andrew Little has announced a Labour government would fund a network starting in the central city and ending in Mt Roskill.
He proposed splitting the estimated $1.36 billion price tag with Auckland Council.
He said the network would help tackle the city's worsening congestion problems as Auckland is crying out for innovative infrastructure projects to get the city moving.
The city's new mayor Phil Goff agreed, but questioned whether the council should have to put anything toward the network, as it could be treated as a road of national significance, and be fully funded by central government.
"It will be carrying far more passengers than many other roads around New Zealand that are funded 100 percent, so we'd want to negotiate between the Labour Party position of 50 percent funding and what would currently be paid for a road of national significance by central government, which is 100 percent," he said.
But Mr Goff was not fully ruling out some contribution.
"Well look, I think Auckland's prepared to meet its share of the cost.
"But as long as the 45,000 extra Aucklanders that we're adding to the city each year are paying almost all their tax to central government through income tax, GST and company tax, then obviously meeting the cost of those 45,000 does need to be met through revenue sharing between central and local government."
Mr Little said the project would depend on some contribution from the council, but acknowledged there would have to be discussions and negotiations.
"I think New Zealanders outside of Auckland would expect there to be some contribution by those living in Auckland who will get, obviously, the immediate physical benefit of it."
Mr Little said he would be open to looking at other options for the council to come up with its half, including a regional fuel tax, if it could not raise the money by other means.
'Panicky' transport pledge - Key
Prime Minister John Key said the timing of Labour's vow to fund a light rail network was all about the upcoming Mt Roskill by-election.
The announcement was "panicky", Mr Key told Morning Report. "They're obviously announcing it around the by-election because they want people to read the ticker-tape and not to push it any further."
Mr Key said light rail projects were "notorious" for going over budget, so the price tag would be much more, and it was yet to be determined whether rail would be more effective than a rapid bus system.
"I think you've really got to do that proper work on whether rapid bus might better than light rail.
"You wouldn't want to race out there with what is a $1.4 billion promise but in reality will be more than that.
"That's quite an expensive promise to win a by-election for a seat they've held for a very long period of time when ... other new Zealanders and other Aucklanders are going to have to pay for that."
National came in for heavy criticism when it promised the people of Northland about $60 million to upgrade 10 bridges during the Northland by-election it later lost.
But National's campaign manager Steven Joyce said that paled in comparison to Labour's light rail announcement.
"This is taking pork-barrel politics to a whole new level," he said.
"If this is the sticker price for a Labour party by-election campaign, all the other electorates across New Zealand will be asking for their $1.4 billion."
Mr Joyce said the announcement showed Labour was already worried about losing Mt Roskill, and they were "hitting the panic button" early on.
Mr Little said Mr Joyce and the National Party were contradicting themselves.
"They accuse us of desperation and then spend the rest of the time saying we're a shoo-in to get it.
"We're working pretty hard to win Mt Roskill, on this particular policy announcement this is a project that's already been slated, it's already been agreed to in various public plans."
Mr Little said Auckland Council had the network as part of its 10-year plan from 2016, but that was pushed out to 2029 under the government's Auckland Transport Alignment Plan. He said Labour would fund the government's half from unallocated funds in future years of the National Land Transport Programme.
National's candidate for Mt Roskill, Parmjeet Parmar, told Morning Report Auckland's congestion needed fixing now and light rail would not help that any time soon.
Labour Party candidate Michael Wood said Ms Parmar's proposals would be tinkering around the edges with the transport problem.