The Reds were linked with a move for the talented Frenchman during the summer, and are now keen to sign him on a 93 day loan before making the move permanent in January.
However, the League One side are not interested in selling the 25 year old, who they signed from Saint Etienne last summer.
Sako has made 48 appearances for Wolves, scoring fifteen goals in all competitions, including four in eight League One games this season, helping his side to third in the division.
The Black Country club value the one time France U21 international at £4m, and have held firm on their stance, stating that they are not encouraging any interest.
The player, who pulled out of training today with an illness, is 15/8 to get on the score-sheet against Colchester United on Saturday afternoon.