Campbell: Portsmouth must buy in January
Campbell is now hoping owner Sacha Gaydamak will back Redknapp with yet more cash.
"If the club wants to move on they've got to put their money where their mouth is," insisted Campbell. "It's a good time here at the moment but if we're not careful it could quite easily go the other way. The new stadium is all ifs and buts, the training ground the same.
"Hopefully they will come but we're all waiting. I don't see the chairman really. Sometimes you see him, sometimes you don't."
Redknapp has already bemoaned the possible impact of the African Cup of Nations which begins next month as Pompey could lose four of their squad for at least a month.
"The African Nations Cup is going to hit us and I hope we can cope," said Campbell.
"It depends if the money is available. We do need to strengthen the side because to lose those guys for a month or six weeks is going to hurt us.
"One or two additions in the right positions would be fantastic but whether that comes true is another thing."