The Championship outfit are in the middle of a takeover and currently have a transfer embargo placed on them by the Football League.
Rooney can only secure players on half-year loan deals and free transfers.
"It's a challenge," Rooney admitted, per the Daily Mirror, following his side's 2-1 friendly loss to his old club Manchester United.
"It's not ideal and is something which I'm constantly aware of and am constantly trying to get answers.
"At the minute I'm still not getting what I want so I have to just focus on the players. I'm not 100 per cent sure of the ins and outs of it (takeover), so I just have to focus on the football
"Something has to happen. It has to.
"For instance, if you look at my squad of players then if nothing changes I haven't got a centre-back.
"In order for us to compete this season, something has to give. I'm preparing the team on the basis that it does happen.
"Otherwise I'm probably down to seven or eight players.
"I'll do my best for this football club. They've given me an opportunity in management.
"Of course I need help with what's going on. I believe that support will come.
"I could do with it now! I could do with it quicker than where it's been but I have to just be focused on the lads and be confident it will happen."
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