Spurs have decided rather than signing an outright replacement for Kane they will spread the goals across the squad, and the imminent push to sign the 22-year-old, who can play across the forward line, is part of that strategy.
Forest do not want to lose a player who scored 10 goals, and added three assists, last season and will demand £50million for Johnson, who is homegrown.
Spurs are unwilling to pay that much for Johnson and will attempt to negotiate a lower fee.
Asked on earlier this week if Spurs must sell before they buy again, manager Ange Postecoglou said: “Not necessarily. These kind of things are pretty fluid, they can happen pretty quickly.
“At the moment you can see by doing the maths we have got too many players in terms of when we submit our final list, there will be guys here who won't be on that list if nothing changes so I am pretty sure that will change. From now until the end of the window I am sure there will be some movement.”