Labour's new leader Jacinda Ardern is set to take her first big political gamble today - asking Aucklanders to partly pay for a proposed rapid transit network.
Ardern will unveil her plan at 1pm in Auckland's Wynyard Quarter - the proposed city terminus for a light rail link down Dominion Rd to the airport.
Two hours later, Prime Minister Bill English will be at the Papakura railway station to announce National's own transport plans for the city, which are expected to include extending the electrified rail line from Papakura to Pukekohe.
Both parties propose spending billions to fix the region's traffic congestion, although National's Transport Minister Simon Bridges said last night: "It won't be a spending competition from National's perspective."
Labour's Auckland issues spokesman Phil Twyford said the parties would offer "two very different approaches".
"Labour's approach is to build a 21st-century rapid transit network for the city," he said.
"National's approach is mostly to continue building roads and motorways."
He said Labour had been influenced by the Greater Auckland lobby group, which proposes a "congestion-free network" including light rail from the airport, up what is now the Northern Busway to Orewa and along the northwestern motorway.
The group says its plan would cost $13 billion to $14 billion, about one-sixth of the $84 billion 30-year plan for Auckland transport already agreed in principle by the Government and Auckland Council.
Twyford said Ardern would also reveal today how Labour would close a funding gap of at least $4 billion for the first decade of the agreed plan.
"Auckland is a third of the country by population, so it's fair that the Government contribute its share towards the National Land Transport Fund, but we have to find ways of making Auckland's growth self-funding," he said.
"That's why we will be announcing various ways in which Aucklanders will contribute to the cost."
Auckland Mayor and former Labour MP Phil Goff has proposed a regional petrol tax in the short term and eventually some form of "congestion charging" - effectively electronic tolls on all roads in the region.
The Government and council have agreed on "smart pricing" in the second decade of the 30-year plan, from 2026, but Bridges said the Government was "hugely sceptical" about a regional petrol tax.
"You would see significant leakage over the [regional] border to different petrol stations, particularly from heavy vehicles," he said.
Greater Auckland spokesman Patrick Reynolds said leakage would be "insignificant".
"If someone wants to drive 50km to get 5c off their petrol, they're welcome," he said.
However a regional tax may have to be much more than 5c. The current national petrol tax of 66.5c a litre (excluding GST) raises $1.9 billion a year, or about $650 million in Auckland, so even an extra 10c a litre in Auckland would raise only about $100 million a year towards closing the funding gap.