Longstaff had a season-long loan at Aberdeen cut short late last year after finding himself out of Stephen Glass’s side, and the midfielder – who signed a new two-year deal at St James’s Park last summer – could be farmed out again before Monday night’s deadline.
However, the 21-year-old, the brother of 24-year-old United midfielder Sean, wouldn’t need to be included in Newcastle’s 25-man Premier League squad because of his age if he stays at St James’s Park, and Howe has a decision to make.
“We’ll see with Matty,” said United’s head coach. “I’ve had limited time to view him and assess him.
“First and foremost, I’ll say he’s very much like his brother, a great lad, really enthusiastic, very passionate about the football club. Very impressed by him as a person and human being.
“In terms of his career going into the latter part of this season, we’ll have to make a decision in conjunction with him and see what the future holds.”
Longstaff made a stunning first-team breakthrough at Newcastle the season before last. He scored against Manchester United on his Premier League debut – and also netted at Old Trafford that season.
However, Longstaff found himself on the fringes of then-head coach Steve Bruce’s squad last season amid talks over a new deal at the club.
Longstaff – who made five appearances for Aberdeen – travelled to Saudi Arabia, for this week’s training camp in Jeddah.