The Spireites are keen to sign the former Wolves trainee, who has rejected the offer of a new contract at Vale Park, and have had one bid turned down.
Any deal rests on whether the two clubs can reach a settlement as the Valiants are entitled to compensation with Morsy under the age of 24.
Morsy's agent Matt Kleinman said: "I know Chesterfield have been in contact with Port Vale about trying to do a deal for Sam to move there, but I don't believe that the two clubs have agreed anything yet.
"The situation is quite straightforward. Sam is technically out of contract with Port Vale. They offered him a new deal which has not been accepted and Port Vale have since rescinded their offer because he did not come back and accept it.
"So at the moment Sam is due to go back to Port Vale to do pre-season training there and he will continue to be paid in accordance with his previous contract until a club comes in and makes an offer that Port Vale deem suitable to take him away.
"Chesterfield have made an offer but at this stage I believe it has not been accepted and talks between the two clubs remain ongoing.
"I don't know how far apart the two clubs are in terms of their valuations of Sam, and neither is it something I would get involved in.
"At this moment in time he remains at Port Vale although technically he hasn't signed a contract with them."
Kleinman added: "But Chesterfield is something that interests Sam. Chesterfield want Sam and he would like to join. Hopefully the two clubs can work something out."