Fox signed from Walsall a year ago and has played 42 games for Coventry City. The Under 21 international has been widely tipped to have a promising international future.
Fox, who plays at left back is being targeted as a potential replacement for Spaniard Jose Enrique who is thought to be leaving the Magpies and go to either Celtic, or Athletico Madrid.
A fee of around £1.6 million plus add-ons, and is expected to be completed in the next few hours.