De Bruyne, on-loan at Werder Bremen this season, is wanted by Bayer as part of the deal which will see Schurrle move to Stamford Bridge at the end of this season.
Voller confirmed: "There are a number of factors, and if I'm honest, De Bruyne is part of it. De Bruyne is a great alternative. He can play a similar position as André.
"If we lose a good one, we just have to get a good one or better. So long as we do not find reasonable agreement, André will stay with us."
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