Mourinho’s side lie eighth in the Premier League table, eight points behind the fourth-placed Gunners, who they host at Old Trafford on Wednesday night.
After playing Fulham this coming weekend, they then face a trip to Anfield for a clash with Jurgen Klopp’s unbeaten Liverpool side.
Speaking on Love Sport Radio, ex-United man Tonge, who left the club for Exeter City in the early 90s, believes that the run of fixtures could be crucial to Mourinho’s future.
He said: “He's got to try and find something from the bottom of the well because there's a lot of vultures hanging around and they've got a bit of a tough period.
“Fans are starting to boo a little bit after games and he is under a lot of pressure at the moment.
“It's a confidence game at the end of the day and United's confidence is low at the moment. We're not firing, we're not united and we're not pulling together.
"Jose comes out and points fingers sometimes.
"Something is not quite right in the club at the moment and it's not just Jose. Some of these players are not stepping up for him.
"There seems to be a bit of turmoil in some of the senior stuff in the club. Ed Woodward's come under criticism. It's a collection of things rather than just pointing fingers at one person.
“I don't think they don't want to play for him. I wouldn't like to think that at a club of United's stature. It's not correct.”
He added: "The injury problems will open up opportunities for other players and it's up to these other players to try and stand up and be counted, like McTominay and a couple of fringe players who will get run-outs. It's up to them to grasp the nettle and crack on.
"It's not been a great start to the season at all and it comes down to the pre-season for me. This is where all these problems started with the lack of transfer activity. I think that's the source of all these problems."