The two clubs are still haggling over a price for the fullback.
While Wilder acknowledges that Spence wants to depart the Riverside Stadium this summer with eyes fixed on north London, he says the financial aspects of the deal must make sense for “reasonable" Boro, who will have no problems reintegrating him into their first-team squad if an agreement cannot be reached.
“If nothing happens with Djed, then he's our player and he'll be back for pre-season," Wilder told the Northern Echo. “From my point of view, negotiations between us and Tottenham stay between us and Tottenham.
“If the deal doesn't get done, we'll see where we go from there. Have I got an input into it? Yeah, 100 per cent. The boy obviously doesn't want to come back here, which I've got absolutely no issue with. He obviously sees his future away from here, and he had a brilliant season last season.
“We're expecting that deal to happen, but if it doesn't, then he's our player. From a club point of view, the deal has to be right. We're not trying to stand in the way of anybody. I've never done that as a manager, and I've had plenty of situations before where opportunities have come along to players.
“But there's always three parties involved in any deal, and it's got to be right for all three parties for it to happen. It's got to be right for the player, and obviously from the noises, it sounds as though that's (Spurs) where he wants to go. Tottenham want him, and we're prepared for that. But it's got to be right for us too. It all needs to marry up."