Newcastle Thunder assistant coach Mike Grady has resigned with immediate effect.
Grady joined the coaching team in the off-season, having spent two years as South Wales Scorpions head coach.
"We'd like to thank Mike for all his efforts," head coach Mick Mantelli told the club website.
"The distances involved have proved a barrier to Mike and we are grateful that he has flagged this now rather than halfway through the season."
Former Canberra Raiders coach Mantelli and assistant coach Michael Heap both remain at the club and will continue to prepare the team for their home game against North Wales Crusaders on Sunday.
Mantelli added: "We will now take our time before filling the position.
"There are a number of aspiring coaches both in the north east and wider afield and it gives a real opportunity to the right person."