The priority is to bolster the defence, with the team still looking for their first clean sheet in the Premier League this season.
Players are likely to go out the door to make room for new arrivals in the squad. Midfielder Dan Gosling and striker Ashley Fletcher are struggling for minutes and Championship clubs are monitoring their situations.
Centre-back Christian Kabasele, who has struggled with his fitness this season, has also been linked with a move to Udinese. The Italian club share the same owners as Watford.