The Portuguese boss will also have to offload expensive players from the Italian side's wage bill to afford the £16.6million former Arsenal captain.
According to Italian news outlet Corriere Dello Sport, Xhaka has 'always been Mourinho's main goal to reinforce the midfield' despite a collapse in negotiations to sign him in the summer.
That was due to a disagreement on an appropriate transfer fee, although relations between the two clubs appear to remain healthy, with Mourinho bringing in Arsenal starlet Ainsley Maitland-Niles on loan earlier in January.
The Serie A side have also signed Sergio Oliveira on loan from Porto to bolster their options in the middle of the park, however the Switzerland national team captain remains in Roma's plans for this transfer window.
Although a move to Stadio Olimpico for Xhaka would seem a sensible move for all parties following the 24-year-old's roller coaster experience at the Emirates, the Gunners' current squad depth issues may mean that now is not the right time to give Xhaka away.
Arsenal's midfield options are strikingly thin, with players suspended and Mohamed Elneny still on international duty at the Africa Cup of Nations, leaving Albert Sambi Lokonga to act as their go-to.
Reports have suggested that the Gunners have been actively searching for midfielders in the transfer window to solve their selection woes, being in the mix for Wolves star Ruben Neves.
However, it is claimed Wolves are confident they can keep hold of the fan favourite for now - with the hope that qualifying for Europe could even convince him to stay beyond the summer, with Manchester United also linked with an interest.
And it's not just Arsenal's transfer business that leaves Xhaka's move to Italy hanging in the balance.
Corriere Dello Sport have reported that Roma will need to sell Amadou Diawara in order to afford to bring the Gunners man to the club and, whilst there has been interest for the Guinean, it has been to no avail.
Valencia had a bid rejected for the midfielder, whilst promotion-pushing Fulham and Torino have both failed to garner the player's attention.
Given the short length of time left in the January window and the tricky circumstances the deal is dependent on, Mourinho may, as he suspected, have to wait until the season's conclusion to push for Xhaka for a third time.