The Potters have been in negotiation with Blues, relegated from the Premier League last season, for a number of weeks and the two clubs appear to have come to a valuation acceptable to both parties.
"We have made an offer and are hoping to do a deal that will satisfy both clubs," chairman Peter Coates told The Sentinel.
"It is my understanding we were very close to a deal but then you still have to sort things out with the players. These things can take forever.
"You have to have other irons in the fire because so many things can go wrong.
"Sometimes you think you have a deal and it doesn't happen.
"As one agent once said, 'The truth today may not be the truth tomorrow'."