Former US President Barack Obama will finally go ahead with his promise to visit New Zealand on a trip in March.

The Herald on Sunday understands Obama will visit on about March 21 arranged by Air New Zealand.

It is understood the contract is due to be finalised and the visit announced next week.

The reason for the visit is unknown but there has been speculation Air NZ is about to launch a new route to the United States, likely Chicago which is Obama's hometown.

Former Prime Minister Sir John Key is now on the Air NZ board and will have been instrumental in securing the high-level visit due to his relationship with Obama when the two were leaders.

Key and Obama played golf together in Hawaii in 2014 and it is understood a rematch is on the agenda for Obama's New Zealand visit - likely in Key's favourite spot of Queenstown.

The visit will likely carry a stiff price tag for Air NZ. According to US media, Obama was securing about $400,000 in speaking fees alone in the United States.

Obama has often promised to travel to New Zealand but did not do so while he was in office.

Key and Obama were elected within a week of each other in 2008; both had holiday homes in Hawaii and they spent five hours on the golf course in 2014 in Hawaii as well as rubbing shoulders at international summits.

Obama shared his thoughts about Key during a conversation with Australian Prime Minister Malcolm Turnbull during the APEC Summit in Manila in 2015.

"John is a wonderful guy and he and I have become good friends. And not just because we play golf together," he told Turnbull.

Last year there was a false alarm of a visit after security detail were spotted in Queenstown - but that turned out to be for a meeting of Five Eyes intelligence officials.

Just before Obama's presidency ended, the then US Ambassador to New Zealand Mark Gilbert said Obama did intend to visit but possibly after he left office.

The last President to visit was Bill Clinton who came in 1999 for the APEC Summit - a visit that included a game of golf with former Prime Minister Jenny Shipley's husband Burton Shipley.

Clinton returned after he was out of office in 2002 to launch a new BMW.