Its involvement has not changed since it teamed up with the NZ Super Fund two years ago, or since Peters and the Cabinet gave Twyford the green light last year to look into it further.
If it was a deal-breaker today, it should have been a deal-breaker back then.
Exactly which party is the most culpable is arguable.
What is not in contention is that management of the Coalition is a growing headache for Prime Minister Jacinda Ardern less than three months from the election, or at least perception of a Coalition at odds.
In fact Labour and the Greens are well used to New Zealand First using its muscle.
Transport Minister Phil Twyford. Photo / Mark Tantrum
But the lack of delivery and Government management will be the story of the election.
In that sense, the light rail issue at this time is not just a present to National, it is gift-wrapped with a blue satin bow.
It is the third issue this week on which New Zealand First has blatantly wielded its power to block or change measures. It is holding up a previous agreement for binding arbitration to resolve commercial lease disputes affected by Covid-19 and it is withholding support for changes to rape trials which many lawyers think will convict the innocent.
Ardern and Twyford are right to remind voters that the way the numbers fell, means that each of the three parties, Labour, New Zealand First and the Greens, must agree to every new policy that was not spelled out in their agreements or Speech from the Throne.
Light rail was in the Greens agreement but in weak language.
"Work will begin on light rail from the city to the airport in Auckland."
Deputy Prime Minister and New Zealand First leader Winston Peters. Photo / Mark Mitchell
It was readily agreed to by Ardern during negotiations after the election because it had been the first promise she had made after being elected Labour leader.
She had no reason to believe that New Zealand First would not support it - it was a very pro-rail party and did not differentiate at that stage between light rail and heavy rail (which it supports).
For that reason, and some unrealistic timelines attached to Ardern's promise, it has been called a flagship policy, much like Kiwibuild.
But Ardern herself and the Cabinet have been more involved in each step of the mega infrastructure project.
Sacking Twyford for New Zealand First's action would be unfair and accentuate her own role.
It won't happen. A line has been drawn under the bid involving foreign interests but it means a clean slate for each party in the election.
