The midfielder has been the subject of interest from several Championship clubs, and Bruce admits his short-term future lies away from St James’s Park.
"It’s something we’ve decided that might be best for Matty. I’ve had that conversation with him,” Bruce said.
"We’ll see in the next week. We’ve had one or two enquiries, we hope something happens for him in the next couple of days.”
It is likely Longstaff will need to sign a contract extension before going out on loan as he enters the final year of his current deal.
Longstaff, who scored the winning goal at home to Manchester United on his Premier League debut, committed his future to his boyhood club last year, despite strong interest from Italian side Udinese.
His new and improved two-year contract had expected to prompt regular gametime, however that has not been the case as he made just four league starts last season.
The summer window slams shut on Tuesday, August 31 at 11pm.
Newcastle face Burnley and Southampton at St James’s Park before the transfer deadline, and Bruce is targetting back-to-back wins.
He said: “There have been a lot of positives in the last two games - there was nothing in the game at all last weekend. And for large periods against West Ham we did OK.
“But you are judged on results and we have to think 'can we get through'? And can we get a result on Saturday that will get us up and running?”
We’ve gathered the best of today’s Premier League speculation below…