Newcastle chairman Freddy Shepherd has called for Sir John Hall to end the uncertainty over the north-east club.
The Magpies have been the subject of takeover talks, with former chairman Hall thought to be keen to offload his shares in the Premiership outfit.
Shepherd said: "Sir John Hall has to decide what his role in the club is. The future of the club is in his hands.
"He has to decide whether he wants to stick or sell. The uncertainty is making it hard for me to run the club."
Last week the Belgravia Group announced it was no longer considering making a bid for the club.
And earlier this month the Polygon hedge fund also pulled out of discussions over a potential buy-out of the Magpies.
Shepherd added: "He is perfectly entitled to sell his shares to whomever he wants. But if he wants to sell them, he needs to say so and if, he does not, good, let's all march on together.
"Sir John identified two potential buyers and it has not worked. How many more potential buyers has the club to cope with?"
"The club simply cannot go on dealing with proposed buyers knocking on the door who turn out to be time wasters"
"For the sake of the club, the shareholders and supporters, Sir John must decide quickly what he is going to do and make his position public.
"The offer period has been damaging and difficult for everyone at the club.
"Everyone at the club, from me as chairman down to the manager Glenn Roeder, the coaches, the players and our administrative staff, have been left wondering whether they would have jobs when it was all over.
"If he lives to be 100, is Sir John going to keep trying to sell these shares? Are we going to have this uncertainty forever?
"I want him to be honest with me and the supporters. The club simply cannot go on dealing with proposed buyers knocking on the door who turn out to be time-wasters.
"It is me who has to run the club on a day-to-day basis and this situation is not conducive to running a huge Premiership club.
"Our fans read that Belgravia were supposedly going to put £24m in for new players in January.
"That conjecture created problems by raising fans' expectations and causes clubs to raise their prices when we ask them about players."
"I could sign a bad player every day between now and 31 January"
Shepherd, who has a 28%-plus holding in the club, also revealed he might consider buying the Hall shares himself.
He said: "I have shown my commitment to Newcastle by buying shares in the club and I have never sold a share. I would consider buying the Hall shares at the correct price.
"I cannot prevent Sir John selling the shares he controls but I want it to be to the right people. As long as I am here, I am going to do my best for the club.
"But at the same time, I am not going to let any would-be buyer take the mickey out of this club or its supporters by raising false expectations."
Hall stood down as chairman in December 1997, with Shepherd assuming control.
Meanwhile, boss Roeder admits he is struggling to land his transfer targets but insists he will bring in new faces, even if only on loan.
He said: "I could sign a bad player every day between now and 31 January. There are plenty out there.
"I am trying to sift through what is available and what can help us on loan until the end of the season.
"I have targeted four or five players I would like to buy, who would help us become a better squad and a better team, but we are finding it hard to prise them from their clubs in January.
"I am determined to use two loans but there is not a lot out there. I will find two though."