Chairman Tony Hewitt says Saints still have room in their budget to make ‘one more good signing’ to replace Samu Manoa.
The American star will move to Toulon this summer after agreeing a four-year deal at the Top 14 giants.
And with his countryman Cam Dolan also departing, it leaves Saints with just Jon Fisher and Sam Dickinson at No.8.
That means director of rugby Jim Mallinder will be keen to bolster his squad further.
And Hewitt said: “We have to stay within the salary cap structure.
“We’re possibly looking for another forward to continue our building of the squad.
“It’s probably one more player, that’s what we’re looking at.”
And he added: “We’ve got a new second row in Michael Paterson and with Samu having covered both the second row and No.8, what we’re looking for now is a No.8 as well.
“We’ve got provision to make one more good signing and that’s where we are.
“We strongly believe in the salary cap because it suits the model we have here at Northampton, which is to run a sustainable business that makes a profit.
“We pay up to the maximum of the salary cap and that keeps the whole thing going.
“If the salary cap was done away with it would be dominated by a couple of teams that have billionaire owners who want to throw money at trying to get success.”