Nainggolan is on-loan in Sardinia from Inter.
"It's clear that, after what is happening, to think that Cagliari will be able to afford the wage of Nainggolan is quite unrealistic," Passetti told La Domenica Sportiva.
“The talks between the parties can make the difference. We will talk about it with Radja and we will talk about it with Inter. We will see if there are the conditions to build something together."