Harley spent a couple months on loan from Fulham last season as well as seeing his three month loan at Bramall Lane cut short after an injury this season. Since then he has been loaned out to West Ham United where Alan Pardew remains uncertain about his career at Upton Park.
The Hammers had expected to be making a move for the former England U-21 Defender after his three month loan spell but Pardew surprised the Football World when Harley was released early.
However Blades boss Neil Warnock is pondering a move for the Left-Back who won the hearts of the fans, who would welcome a Harley move.
Warnock Said; "I would never say never to signing someone like Jon. He's quality."