The winger has a release clause in the contract he signed in January after a £12million move from Tottenham Hotspur.
And the relegated Magpies fear they will lose the England international, who is set to report back to the club at the end of the week for the start of pre-season training.
Townsend hit form in the latter part of last season and narrowly failed to make Roy Hodgson’s Euro 2016 squad.
A clutch of clubs, including Crystal Palace, are ready to offer Townsend a Premier League lifeline.
The 24-year-old is available for £10.5million due to the clause in his deal, though he has not given any public indication that he is looking to leave Newcastle.
However, United acknowledge that there is a strong chance he will opt to quit and stay in the top flight.
The weekend saw Newcastle linked with Bournemouth winger Matt Ritchie.