The centre-half, who enjoyed a great loan spell at Brighton last term, has been earning mixed reviews at Stamford Bridge this term.
Colwill, who can play as a centre back and a left-back, is only 20 years old.
Per talkSPORT, Liverpool are serious about bidding for the youngster in the summer.
They retain an interest" in Colwill according to the source, which outlined the reasons for a possible sale.
Given Conor Gallagher is not moving to Tottenham, Chelsea may need to sell a youth product this winter or in the summer.
