National's health spokesperson Tony Ryall says a health budget surplus will pay for after-hours health care for children aged under six if the party is re-elected in November.
National announced the plan to provide free after-hours visits to the doctor on Thursday.
At present, 87% of children under this age get free visits to the doctor because their GPs have signed up to the scheme.
Extending it to after-hours will cost about $7 million a year, but Mr Ryall says it is not a vote grabber.
Mr Ryall told Radio New Zealand's Morning Report programme on Friday the National Government has under-spent on some projects, sought best prices and has not spent all its budget in some areas of health.
Mr Ryall says the scheme was successfully rolled out in Auckland earlier this year, where seven out of 11 clinics are free care to children aged under six with very good take-up.