SUNDERLAND have begun the process of conducting formal interviews for their vacant managerial position, but chief executive Martin Bain is determined to conduct a thorough process of due diligence before settling on his preferred candidate to replace Simon Grayson.

It is now two weeks since Grayson was dismissed in the wake of a 3-3 draw with Bolton Wanderers, but Sunderland are yet to appoint his permanent successor despite the international break having provided a logical hiatus in which to conduct their business.

Robbie Stockdale finds himself in sole caretaker charge of the club following Billy McKinlay’s weekend departure to join the coaching staff at West Ham United, and has begun the process of preparing to lead the team in Saturday’s home game with Millwall, but some supporters are growing increasingly frustrated at the length of time it is taking for a long-term decision to be made.

Sources close to the recruitment process insist that there has been progress in the last few days, and Bain has spoken to at least two potential candidates to discuss their interest in the role. The talks are understood to have taken place in Manchester and Leeds, but while they progressed to the stage of a more formal interview, the Black Cats chief does not yet feel ready to make a binding job offer.

Last summer’s appointment of Grayson turned out to be a major disappointment, and with Sunderland sitting at the foot of the Championship table, there is an acceptance that another unsuccessful decision could have devastating consequences.

Bain is canvassing opinion from a number of quarters, with academy chief Jimmy Sinclair understood to be playing a prominent role in the recruitment process. Sinclair was appointed as academy director in February, having initially worked with Bain during his time as chief executive of Rangers.

A number of candidates have been discussed, with former Middlesbrough manager Aitor Karanka and current Barnsley boss Paul Heckingbottom remaining in the running. Karanka is keen to return to management in England having been out of work for eight months since his dismissal from the Riverside, while Heckingbottom won a number of admirers as he guided Barnsley to victory in both the Football League Trophy and League One play-off final last season.

Ally McCoist is another name under consideration, although the former Scotland international has not been involved in frontline management since leaving Rangers in 2014.

John O’Shea continues to be linked with a managerial position, having expressed a desire to move into coaching once his playing career ends.

O’Shea is part of the Republic of Ireland squad that will attempt to qualify for the World Cup finals when they play the second leg of their play-off with Denmark tonight, and the result of the game in Dublin could go a long way towards deciding the defender’s future.

If Ireland fail to qualify, O’Shea could decide to fast-track his coaching and managerial aspirations despite having started Sunderland’s last six Championship games. If Martin O’Neill’s side were to make it to Russia, though, he might be much keener to focus on playing in an attempt to claim a place in Ireland’s World Cup squad.

Northern Ireland will not be involved in next summer’s finals after Sunday’s goalless draw with Switzerland meant they suffered a 1-0 aggregate defeat in their own play-off game.

Their failure to qualify has led to speculation suggesting Michael O’Neill will opt to stand down as Northern Ireland boss in order to pursue a new challenge, and the former Newcastle United defender has been linked with a possible role with both Scotland and Sunderland.

O’Neill is refusing to discuss his future at this stage though, insisting he wants to take his time to reflect on Sunday’s disappointment.

“I’m contracted until 2020, and tonight is about me being there for my players,” said O’Neill, in the wake of his side’s goalless draw in Basle. “That’s it – I’m not looking any further than that.”