Campaign chair Simeon Brown earlier compared National's coalition partners to children.
The Prime Minister believes it would be difficult for other parties to argue against the KiwiSaver changes National is proposing, and is keen to see some cross-party buy-in.
The party's campaign chair has launched a new attack.
National would automatically enrol babies and make KiwiSaver compulsory for all workers.
OPINION: National plans to make KiwiSaver compulsory for workers and employers.