National's promising to build a second Mount Victoria tunnel in Wellington in their first term, if they're in Government.

National Leader Chris Luxon sat down with Nick Mills on Wellington Mornings for half an hour and said they'll fast-track consents for that and upgrading the Basin Reserve.

He's also not putting too much stock in Roy Morgan's latest political survey, which has National falling by 2.5 points to 31.

LISTEN ABOVE