The Daily Mail says the 20-year-old was absent from the Shrimpers side on Tuesday and could now be set for Old Trafford. His manager Sol Campbell has confirmed rumours of an exit and said he is on the brink of leaving - although he claimed he didn't know which team he would be signing for.
"He's having a medical," said Campbell. "I don't know where but if he passes the medical he's gone."
Bishop, who is an England Under-20 international has played 17 times for Southend in League One this season.
He started his career with the Shrimpers and made his debut for the club in the 2017-18 season.