Spurs boss Harry Redknapp is keen on signing Downing in the January transfer window, but Boro are looking for a big offer.
The 24-year-old signed a five-year contract earlier this season and Boro want at least £15million for their star winger.
Boro have previously been offered Spurs fringe players Hossam Ghaly, Gilberto and Adel Taarabt as part of a deal.
