The Newcastle United midfielder – who broke into Bruce’s first-team squad last summer – is out of contract at the end of the season.
And talks over new deals for him and his elder brother Sean, which are being led by managing director Lee Charnley, have been stalled for several months.
Matty’s situation has added urgency given that he is free to leave at the end of the campaign, and Bruce has called on the club and Longstaff’s representatives to meet in the middle.
“Matt is the most important one, because his deal runs out,” said Bruce, United’s head coach. “Obviously, he’s got advisers, who’ll be advising one thing. I’m desperate for him to stay, but there’s got to be ground given on both sides, I would’ve thought, but, at the minute, we can't get there.”
Rafa Benitez and Alan Pardew, two of Bruce’s managerial predecessors, had some success in helping to resolve contract disputes. Bruce, however, won’t get involved.
“I will be kept abreast of the situation,” said Bruce. “But one thing I’m not going to get involved in nowadays is contracts. Back in the day, I had (rows) over contracts and money.
“Both sides have got to be happy and at the minute, there’s a bit of an impasse, but I’m confident we’ll still get it done.”
Sean Longstaff – who signed a contract keeping him at United until 2022 last season before he made his Premier League football – was on target in last week’s 3-2 FA Cup win over Oxford United.
The midfielder was still recovering from a knee injury when Bruce was appointed last July.
“I watched him when I first arrived in China, and I knew he wasn't right,” said Bruce. “He was physically recovered, but he couldn’t check and turn. So a lot of it was about coping with that.”
Longstaff, 22, was a target for Manchester United at the time.
“There was a lot of speculation in the summer,” said Bruce. “He had the injury to cope with as well.”