Ole Gunnar Solskjaer is growing frustrated at the slow progress in his summer rebuild.
Further, he perfectly fits the profile of young homegrown talent that the Norwegian is eager for at Manchester United.
Solskjaer had hoped to bring in a number of signings ahead of next season, with a need for added depth in defence and midfield.
It's been a decent transfer window for the Red Devils so far.
The 21-year-old is believed to be in no hurry to leave Tyneside and is expected to remain fully committed to Newcastle, should they fail to reach an agreement with Manchester United.
In a summer where Rafa Benitez and Ayoze Perez have already left Newcastle and the club is even more of a shambles, few would blame Longstaff if he wanted to get out.
Reports earlier in the window suggested the midfielder could be available for £25m.
Ghanaian global, Christian Atsu has been left out of the team list of Newcastle United's pre season tour in Asia.
United also want a new centre-back, with Leicester's Harry Maguire still their No.1 target.
Manchester United's chief executive Ed Woodward held negotiations with Newcastle United MD Lee Charnley this past Saturday when he was quoted the astronomical fee as per the report.
Without doubt, the above mentioned price tag is extremely high taking into consideration that the player has played very few games and he has been out of action since March due to a knee injury.