There's doubt we have enough information to decide whether to increase the retirement age or not

National Party leader Todd Muller says the party will campaign on raising the Super age to 67 by 2040, starting in 2037.

Jacinda Ardern says the age of entitlement won't be increased on her watch.

Retirement researcher ,Michael Littlewood, says we don't have enough information to start a sensible long-term discussion about increasing the age of entitlement.

He says we should step back to ask what we need to know to have the discussion.

Littlewood says there's a heap of information we don't know.