The National Party says it will foot the bill for Auckland's near $1 billion Mill Road Corridor project, taking it off the council's hands, if re-elected to government.

The $955m roading project through Manukau, Papakura and Drury will be declared a state highway, as part of a broader Auckland transport policy announced by party transport spokesman Simon Bridges and leader Bill English at Airport Oaks on Friday.

The party says the change would mean the road would be funded through the government's National Land Transport Fund, freeing Auckland Transport up to use the money elsewhere.

"We know more needs to be done. That's why National is committed to ensuring Auckland's transport needs are met," Mr Bridges said.

National has also promised to work with the council to speed up development of the Eastern Busway, Northwestern Busway and a mass transit solution between the city's CBD and airport.

Mr Bridges also committed a fourth-term National government to starting construction on the proposed $1.85b East-West Link State Highway, building a third main rail line and extending rail electrification to Pukekohe.

Mr English told reporters the decision to take over the Mills Road project was part of an ongoing discussion with Auckland Council.

"Also upgrading it to a State Highway would mean Auckland would have two entrances from the south," he said.

Asked whether the party was focusing too much on roads, Mr English said National had committed to partly funding the Auckland's $3.4b City Rail Link as fast as possible and was also working on improvements to buses and rail across the city.

"It's quite balanced between dealing with the growing volume of traffic and at the same time as investing in the growing patronage of public transport," he said.