After an encouraging start to the season, the Elland Road club have lost their way in recent weeks.
Five defeats in seven Championship outings have seen United tumble from the play-off places to the bottom half of the table.
A further fall is likely today due to Leeds not being in action until tomorrow when Birmingham City are the visitors to West Yorkshire, but McDermott insists that patience is going to be the key to turning things round.
He said: “The biggest friend I have got here is time. I need that time and you get time by winning games. The more games you win the better you become and the more you can evolve the club.
“I need that time and I need the fans to realise that. I have been involved in 19 games (since succeeding Neil Warnock last April) and we have won nine.
“But we have had a run where in seven games we have won two and that is disappointing for all of us.
“We need to look at that and look at why. We have to make sure that we have a winning mentality – and I think you can teach that.
“We have talked about what has gone wrong. But you can talk as much as you like. You have to take that onto the pitch.
“It is a mentality and you have to be strong-minded, ruthless, show real desire. You look at season by season, it goes really quick.
“Soon enough, we will be sat here and the season will be over. I don’t want to be sat here in May saying, ‘If only, if only’. We have got 105 points to play for. Let’s get as many as we can.”
United’s slump in form has been accompanied by something of a goal drought with the recent 2-1 victory over Bournemouth being the only time since August that they have scored more than one goal in a game.
McDermott has been endeavouring to bring in some much-needed firepower during the recent international break but, despite making half a dozen enquiries, he has drawn a blank.
United’s attacking armoury will be further weakened against Birmingham by El Hadji-Diouf being granted compassionate leave following the death of former Senegal coach Bruno Metsu.
The 59-year-old passed away earlier this week and Diouf, who regards Metsu as an inspirational figure, has flown back to Senegal for the funeral.
On United’s need to hit the goal trail and snap out of their current poor run of form, McDermott said: “If you look at the last seven games it has obviously been a difficult spell for us. We need to kick on. We talked about a winning mentality and it is not just about going into a game and playing. It is about getting the job done and winning.
“I know all about this division and I know what it takes. We all do. You win a couple of games you are in the top six, you lose a couple and you’re down amongst it.
“There is not much middle ground in football. We all react off the last result and that is how it is. That is how football is.
“When you win the last game, everyone says, ‘You’re great’. But when you lose, not so much. My view is that it is never as good as you think and it is never as bad as you think.
“There is always pressure at Leeds and you have to live with it.
“The international break came at a good time for us. We could reflect and look forward. We had a really good meeting on Thursday morning about moving ahead.”
Tomorrow looks set to bring the lowest crowd of the season at Elland Road despite tickets being pegged at Category C prices.
Birmingham are understood to have sold only 300 or so tickets for a fixture that will be shown live on Sky Sports. United had been hoping to unveil a new face or two, but McDermott admits bringing in the quality of loanee he wants has proved a challenge.
He said: “I made about six enquiries for players that we targeted and, for whatever reason, we couldn’t manage to get one over the line.
“There were players we could have taken, but I have never been in the process of taking a player for the sake of it. I am not going to start now. There is money available if we can get one or two signings in, if they are the right people.
“I am not disheartened. I am trying to get in players who can make a difference and can galvanise our group.
“We could take a number who would be similar to what we have got and that is not what we are trying to do. I want players who can come straight into the team and make a difference.
“To find those players I’ve made five or six enquiries but it hasn’t happened. I have been a scout for 10 years so this is the story of my life. I could tell you loads of stories about players I missed out on.
“Sometimes you hear from an agent that the player is available. You think, ‘That’s great’. But then you ring the manager of the football club that he plays for and that is not the case.”
One player who has been training with Leeds is former hearts captain Marius Zaliukas, the Lithuanian international defender who made more than 200 appearances for the Edinburgh club.
Match preview: Page 3.