Toro are ready to splash out to buy the Italy U21 midfielder immediately this month - and the move has been approved by Casadei.
TMW says negotiations have stalled over Chelsea's insistence on a buy-back option in the deal.
Toro are reluctant as it leaves them open to losing Casadei with no say.
While offers are arriving from across Europe, Toro for now are regarded as favourites to land Casadei.