Obama is visiting for the first time - and Key told Newstalk ZB this morning it was worth it for the tourism promotion, pointing out Obama has 101 million followers on Twitter alone and is likely to tweet during his stay.

However, there will be precious few opportunities for the New Zealand public to see him.

Obama is visiting as private citizen and there are political sensitivities around how much he can say publicly.

There will be no media interviews or reporting from his speaking event and at previous events elsewhere, those attending have been told not to share the occasion on social media.

On Thursday night he will be at his main speaking event in Auckland. That is being organised by the NZ-US Council and co-sponsored by Air NZ, Westpac and MasterCard.

The invite-only audience of about 1000 will include prominent business people and MPs - about 35 MPs have been invited although Ardern herself will not attend.

Obama is visiting on a trip around Singapore, New Zealand, Australia and Japan – New Zealand can at least claim the lion's share of that week long tour – it has Obama for almost three days while Singapore, Australia and Japan secured less than two days each.