Balde has been considered a late signing but wants to stay at Barcelona, leaving United to assess whether they should pursue another target before the September 1st deadline or show patience and move ahead this season with their existing options.
Jorge Salinas and David Raum remain among a shortlist of left-backs being considered, but sources say there is even a possibility United do not make a signing in the position.
As revealed by Flashscore, United were already cautious about a deal for Balde, and their admiration for Lewis Hall remains strong.
They will only move for Balde now if the terms are tailored to a good-value deal, and the player signals he is ready to change his perspective.
Some within the club now feel it's better to wait on Hall rather than force a deal this summer for someone else. United could look to make a move for him further down the line, following a similar approach to the one they took with Carlos Baleba.
Baleba has now joined United from Brighton for a knockdown £70million after the midfielder had previously been valued at around £100m by his former club last year.
United's short-term concern is simply having enough cover in defence to get through this season.
Boss Michael Carrick has complete faith in Luke Shaw as his starting left-back and continues to view him as a valuable member of the squad.
Any new arrival in the position would initially be expected to support Shaw and provide competition and rotation rather than immediately replace him. United's longer-term preference is to find a player who can eventually succeed Shaw as their first-choice left-back.
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That has influenced the way they have approached the position this summer.
United did not prioritise a major investment at left-back with their transfer budget, instead deciding that strengthening central midfield was a much more urgent requirement. That is why they moved first for three central midfielders and have ultimately been unwilling to pay Newcastle's asking price for Hall.
Carrick felt the need for additional bodies in midfield was greater, meaning the left-back position has remained an area where United have had to balance immediate squad requirements against their longer-term ambitions.
A move for 19-year-old Salinas from Racing Santander remains an ongoing possibility and is one United continue to consider as they assess options. Raum could represent a more trusted deal, with the RB Leipzig defender a name on the club's shortlist and a potentially attainable option before the deadline.
The decision facing United is not simply whether to sign another left-back, but whether the right player is available at the right price. For now, the internal conversations continue.