A downbeat McDonald, who returned to United in the summer as joint plc chairman, admits he would now walk out again if he had the chance.
Carlo Colombotti helps preside over the plc, while Kevin McCabe runs the football club board, although McDonald is seen as United's figurehead.
McDonald, who has a 13.5 per-cent stake in the Blades, said: "I want to get stability at the club and make sure it is working right. Then I will go. It could be tomorrow or next year.
"I don't want to be anywhere where I am not wanted, but on the other hand I have a duty to protect my investment. I have a duty to sort things out and that's why I came back."
Part of McDonald's desire to leave is because of the growing hostility from sections of supporters, whom he criticises in return. "Sheffield fans are fickle," he revealed. "If just 10,000 turn up then players will have to be sold, but it won't be me selling the players, it will be the fans."Reuse content