Guy Whittingham has asked for his Pompey playing budget to be increased to bring in three players he believes can strengthen the promotion push.
The Blues boss wants Ricardo Rocha and Ryan Bird to add to his existing 17-man first-team squad.
In addition, he has identified a central midfielder with League One experience who is currently without a club.
However, to push through all three deals Whittingham’s £1.2m budget needs to be bolstered.
The request is in the hands of chairman Iain McInnes who, along with some of the club presidents, may need to dip into their own pockets to fund it.
Whittingham hopes something can finalised to enable him to land his three targets.
He said: ‘There is no more news on the central midfielder at the moment.
‘We would like it done possibly soon.
‘But we are not sure whether it can be done yet.
‘We are still investigating things and are hopeful.
‘We have done quite well with our budget for the players we have got in.
‘But we are towards the higher end of that budget so we have got to be careful.
‘The new club has been fantastic with us and the fans have been fantastic with us and I am hoping they can help us out – and we are looking at that situation at the minute.
‘It is not necessarily extending your budget – it’s just different ways of doing things.
‘I didn’t think there were so many different ways – I am learning all the time!
‘There are three players we would like to try to do.
‘Massaging it, changing it and looking at ways of doing things, it’s fantastic what people can come up with.
‘The board have been great, they have backed us all the way.
‘I think it has helped they can actually see there’s a decent group of players here that want to do well at this football club and its great fans.’
Bird returns from his holiday in Spain today, although Whittingham says the striker will not be available to face Charlton.
Pompey are also still awaiting a decision from Rocha over his potential return having now set a deadline at the end of this week.
In financial terms, both would have a minimal impact on the wage bill.
But the unnamed midfielder targeted by Whittingham would cost considerably more.
He added: ‘There is nothing about Ricardo yet, while Ryan is back at the end of this week.
‘Ryan is probably not in contention for the Charlton game after being away.
‘We will get him back in and have a good chat with him.
‘He comes back today so we may well see him down here tomorrow (at Colchester).
‘He will be in with us Saturday but it is probably too much to ask for him to play against Charlton, so we are looking more towards Bournemouth.’