Transport Minister Steven Joyce says candidates for the Auckland mayoralty need to consider who will pay for promises being made on the campaign trail.
Mr Joyce told a conference in Auckland on Thursday that talk of a rail link to Auckland's North Shore or the airport could be some way off in the future.
Mayoral candidate Andrew Williams wants a rail tunnel built within eight years, while all the leading candidates are keen on a link to the airport.
Mr Joyce says many roading projects are still to be built and should come before any talk of new rail projects.
Listen to Checkpoint interview with Steven Joyce