Other reasons for delays cited by the council-controlled organisation included a power cut to KiwiRail's train control centre in Wellington on April 26, halting all Auckland services for more than an hour in the evening travel peak.
A recommendation from a hearings panel to add the Pukekohe investigation to the organisation's programme won support from the Citizens and Ratepayers' leader on the Auckland Council, Christine Fletcher, as well as from council transport chairman Mike Lee.
Both are appointees to the organisation's board and Mr Lee headed the former Auckland Regional Council when it asked the previous Labour government in 2008 to add an 18km Pukekohe extension to the $500 million electrification project.
That was estimated to cost an extra $115 million.
Mr Lee said yesterday that a Cabinet decision to make Papakura the southern cut-off point for electrification had been "somewhat arbitrary", and the 20 services a day now running from Pukekohe were "very much an integral part of the rail system".
Across the political divide, Mrs Fletcher said strong consensus was building around the Auckland Council table for electrification to Pukekohe, and she believed it should consider a reprioritisation of other work to allow that to happen.
"No other [transport] project has so much support," she told the Auckland Transport board.
After the board meeting, Mrs Fletcher was reluctant to elaborate on her call for a reprioritisation of transport projects, or to make a direct link with the central rail tunnel.
Although independent right-leaning councillor Cameron Brewer has said it would be crazy to spend $112 million in the coming year on tunnel land purchases without Government backing, she insisted her team was "not opposed" to the project and supported protecting its route.
"We are just unclear at this stage on the sequencing of construction," she told the Herald.
On the other hand, the overwhelming view of those making submissions on Auckland Transport's draft programme was that extending electrification to Pukekohe was "that this is a no-brainer to optimise investment in rail".
Mr Lee was sceptical, saying he suspected Mrs Fletcher was joining the Pukekohe cause as "a face-saving way to justify her weakening on her commitment to the city rail link [tunnel], which she campaigned on".