Highlanders assistant coach Scott McLeod is the dark horse in the race to replace Wayne Smith in the All Blacks.

Scott McLeod and John Plumtree appear the early favourites to take on the All Blacks' defensive coaching role.

With Wayne Smith set to step back from the All Blacks after the British and Irish Lions tour and Rugby Championship, New Zealand Rugby have given themselves plenty of time to openly advertise his role and find a suitable replacement.

Candidates from abroad have been welcomed to apply, but it would run against the grain for a country noted for exporting world leading coaches to appoint a foreigner; someone with limited knowledge of the New Zealand environment.

GETTY IMAGES Hurricanes assistant coach John Plumtree may throw his name in the hat to replace Wayne Smith.

Few overseas-based New Zealand mentors are likely to challenge those plying their trade in Super Rugby, either. That brings us to leading local contenders, McLeod and Plumtree, who appear two contrasting characters.

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The elevation of Highlanders assistant McLeod, the former Waikato, Chiefs and All Blacks midfielder who played 10 tests between 1996 and 1998, would surprise but Smith considers him an innovative defensive coach. The 44-year-old has also worked as an assistant with Waikato and the New Zealand under-20s.

Plumtree, a former loose forward/lock, has added a much harder edge to the Hurricanes forward pack and, crucially, a defensive steel since linking up with Chris Boyd in Wellington two years ago.

In the run to their maiden title last year, Plumtree's systems and strategies were instrumental as the Hurricanes held firm without conceding a try in three home playoff games against the Sharks, Chiefs and Lions.

Taranaki-born and raised Plumtree also has extensive club head coaching experience in Wales and South Africa and is believed to harbour aspirations to be involved with the All Blacks. It is understood that Plumtree's expertise with the forwards, as opposed to Smith's knowledge of the backs, will not count against him.

McLeod and Plumtree are likely to be encouraged to contest Smith's position and Smith namechecked both in a Sunday Star-Times piece about his future last October.

The timing for others in New Zealand does not appear right. Scott Robertson has performed an excellent job with the Crusaders defence this season but is halfway through his first year as head coach and unlikely to step away.

Alistair Rogers, the former All Blacks analyst who worked under Smith, has one of Super Rugby's best defensive records with the Blues this season. But he is in the second year of a major rebuild job alongside Tana Umaga in Auckland.

Andrew Strawbridge handles the Chiefs defence but is not thought to be on the national radar, while Dave Rennie and Kieran Keane have signed contracts with overseas clubs.

With Tony Brown departing the Highlanders at the end of this season to link up with Jamie Joseph in Japan, McLeod is also considered a strong contender to assume the head coach role in 2018.

Should McLeod instead join the All Blacks, Aaron Mauger may have the inside running ahead of fellow Highlanders assistant Mark Hammett for that title.

It is understood All Blacks coach Steve Hansen, assistant Ian Foster and one other NZ Rugby figurehead will conduct interviews for Smith's brief. The role will be solely defensive based, with Foster expected to assume Smith's counter attack responsibilities.

"The hole will be big because this is a guy who has made a massive contribution," Hansen said at the announcement of Smith's pending departure.

"But the systems he has put in place and the structures that go with it, I think will lessen the hole. The hole from the man will be massive but the hole from the rugby side won't be so big."

Smith will help transition the successful candidate through the Rugby Championship before handing over the reins fully for the end of year tour.

There are positive noises about the remainder of the All Blacks management team, Foster and set piece guru Mike Cron in particular, soon committing through to the World Cup in 2019.