Labour says it's still fully committed to its transport plans for Christchurch, as well as a massive investment in the Auckland region.

In June, the party announced a $100 million transport investment in the garden city, to be funded by a re-allocation of the transport budget.

The biggest single project would be a commuter rail link between Rolleston and the CBD.

Spokeswoman for Christchurch Regeneration, Megan Woods, said new leader Jacinda Ardern understands the need for the investment.

"I've spoken to Jacinda this morning, and confirmed we're all good to go on this, and she absolutely is committed to this kind of vision for our city.

"Labour is absolutely committed to having a rail option in Christchurch, starting that with the western line, and that commitment stands."

Dr Woods said the proposed commuter link between Rolleston and the CBD won't be paid for by a petrol tax.

She said the $100 million will come from a re-allocation of the transport budget.