Light rail was a flagship policy by Jacinda Ardern promised at the 2017 election to have the first leg from the CBD to Mt Roskill completed within four years and running the full 22km to the airport within 10 years.
Labour also promised light rail to Westgate in West Auckland - later saying it would go as far as Kumeū/Huapai - before abandoning the idea in 2019.
At first, Labour directed the NZ Transport Agency to lead the development of light rail to the airport, expected to cost about $6 billion.
That all changed In 2018 when the Government received an unsolicited bid from NZ Infra, a joint venture between the NZ Super Fund and a Canadian pension fund, CDPQ Infra, to build the scheme as a public-private partnership.
The then Transport Minister Phil Twyford announced the Ministry of Transport would assess rival bids from NZTA and NZ Infra and recommend the best proposal to Cabinet.
From this point on, the plans for light rail from Wynyard Quarter, up Queen St and along Dominion Rd before straddling SH16 to the airport became shrouded in secrecy.
The Government would not tell anyone in Auckland what was happening.
National's transport spokesman Chris Bishop summed up the confusion in June last year: "We've got no plan, no costings, no consents, not even any idea of the route, no idea who will build it... nothing to show for three years of work."
The ministry recommended the Super Fund's plan in mid-2020, but it was blocked by NZ First, whole leader Winston Peter said it would cost between $10b and $15b and lead to a "decade of chaos".
In November last year, the Auditor-General John Ryan criticised the "parallel process" to have a run-off between NZTA and NZ Infra to select a delivery partner.
The project was taken off the table and referred back to the Ministry of Transport for further work, with a decision left to be made by the new Government.