Auckland Mayor Phil Goff is backing Labour's plan to introduce a regional fuel tax so Auckland can buy its way out of gridlock.
But Prime Minister Bill English says it can't be done, and Kiwi motorists as far away as Invercargill will have to pay up at the pump.
New Labour leader Jacinda Ardern said on Sunday Labour would build rail from the Auckland CBD to the airport within 10 years, paid for with a petrol tax of about 10c a litre. The Government is instead working with Auckland Council on a congestion tax, and has kicked the rail plan 30 years into the future.
"I've got sad news for voters - we're going to have to pay anyway," Mr Goff, a former Labour leader himself, told The AM Show on Monday.
"It might be a fuel tax, it might be... a congestion tax, but either way it's naive to think that we as Aucklanders won't have to make a contribution. We will."
Mr English told The AM Show one of the reasons the Government rejected Mr Goff's proposed regional fuel tax is that it just can't be done.
"They can't target it on the Auckland region. The companies simply pay the bill to the Government and to the council," he said.
"I'm advised there's no way you can actually show the money was collected only in Auckland."
Mr Goff said Transport Minister Simon Bridges has privately told him the Government knows it can't wait 30 years to build rail to the airport.
"We're the gateway city for New Zealand, yet that gateway is clogged. The worst thing you can do to a visitor to this country is say, 'Welcome to New Zealand - by the way, it'll take you an hour-and-a-half to get from the airport to your hotel."
Mr English says the success the Waterview Tunnel has had in easing congestion shows there's no need to spend billions on rail to the airport.
"The thing with Labour is not just the big spending - it's usually just spending without focus on getting results. We're focused on getting results."