Colback accepts his future with Newcastle is over.
He told Nottinghamshire Live: “I have had a lot of people ask me that and it is a tough one to answer. If you ask me if I would like to come back and sign permanently, the answer is yes. It is not as easy as that in football. Forest themselves have to commit to a permanent deal. Then you have to work out that deal.
“It is not as straightforward as a yes or no. But I have enjoyed my time here and, if the opportunity arose, it is one I would view positively, with good thought. I know the club, because I have been there a little while. I know the players, I have enjoyed my time here and my family are happy, so let's see what happens."