Manchester United's plans to bid for Mbeumo have hit a standstill after Brentford increased their valuation of the player to close to £70 million.
Sir Jim Ratcliffe is reluctant to be forced into paying more than the club's £65 million valuation for the forward.
Mbeumo has told Brentford he wants to join Manchester United. At the end of June, Ratcliffe and his football director Jason Wilcox believed a £65 million offer would be enough to sign the 25-year-old, and Brentford had privately indicated that a medical was expected soon.
Ratcliffe and Wilcox have faced resistance over their change in stance, unwilling to be held to ransom and determined to exercise patience.
Brentford are standing firm, confident in their position as, although Mbeumo's contract expires next summer, the club hold a one-year option.
If Ratcliffe and Wilcox, who are in charge of United's football operations, decide to increase their offer, they are likely to first look to raise funds by selling one of Marcus Rashford, Alejandro Garnacho,
Antony, Jadon Sancho or Tyrell Malacia.
United claim that several of these players have offered to leave, and the club will therefore listen to offers for them.
