Newton is currently on a season-long loan at St Mirren and his contract with Newcastle expires this summer.
The news has alerted a host of teams to Newton's expected availability on a free transfer with the talented midfielder impressing at St Mirren.
Newton enjoyed a successful season on loan with the Paisley outfit last season, helping the club win the Scottish League Cup when he scored in the final victory over Hearts.
The 22-year-old has netted four goals in 33 appearances this season and several scouts have been tracking his progress at St Mirren Park.
Teams from the Championship and Scottish giants Celtic and Rangers are believed to be admirers of Newton and are weighing up a move if he becomes available this summer.