Road charges should be brought in urgently to tackle Auckland's chronic congestion, a major infrastructure groups says.
The government now says it backs tolls or roads charges over the long-term.
The Council for Infrastructure Development has said it wants immediate action, as traffic jams are threatening the city's economy.
But some mayoral candidates are against another tax on Aucklanders.
The Council for Infrastructure Development is calling for road charges within five years.
With 800 more cars on the city's roads every week, the group's head, Stephen Selwood, said Auckland couldn't wait any longer.
The government's proposed GPS-based pricing system was risky and would not be ready for a decade, he said.
"The projections within the next decade of congestion on Auckland's road system are pretty dire. By 2026, the inter-peak [period] is expected to be almost as bad as the morning peak is now. And, look, the Auckland economy can't sustain that level of congestion."
Mr Selwood said charges should be brought in gradually across the network, and people shouldn't be priced off the roads.
"You can set the price at a level which is so high that it suppresses travel and means a whole lot of trips don't get made, but there's a huge cost, social and economic cost to those trips not being made."
Mr Selwood said peak-time commuters could pay $3 on the motorway, reduced to $1 or free during off-peak times.
Road Transport Forum head Ken Shirley said the charge could be up to $5 for 10km.
The user charge was better than the drain on business from traffic jams, he said.
"We're philosophically not opposed to toll roading at all. The devil will be in the detail though. As long as it's fair and equitable. It is a user-pay system so we want infrastructure, therefore you've got to pay for it."
But some Auckland mayoral candidates said they wouldn't support another tax.
One candidate, Vic Crone, said the public transport system needed to be fixed first.
"I am supportive of tolls where you are building a new road, but [not] just a general congestion charge when many people, particularly east Auckland and further west Auckland, just don't have an alternative choice."
The Labour Party said it would be unfair to charge Aucklanders thousands of dollars a year in road charges.
But former Labour leader and Auckland mayoral hopeful Phil Goff said it was a good way to tackle congestion, which was costing the city $3 billion a year.
"I think it's far fairer actually to put a charge on that both influences behaviour and raises revenue without requiring rates to rise."
A regional tax could be brought in first until the GPS technology is ready in about five years to be used in a variable road pricing system across the network, he said.