United, under the leadership of Sir Jim Ratcliffe and director of football Jason Wilcox, had believed a 65 million pounds package would be sufficient, with Brentford even privately suggesting a medical was imminent by the end of June.
However, Brentford's change in stance - bolstered by a one-year option in Mbeumo's contract, which otherwise expires next summer - has caused United to reconsider.
Ratcliffe and Wilcox are refusing to be held to ransom and are expected to remain patient. The club is unlikely to raise its offer until players are sold or loaned out.
United are reportedly open to letting go of Marcus Rashford, Alejandro Garnacho, Antony, Jadon Sancho, and Tyrell Malacia - all of whom are understood to have asked to leave.
Funds generated could help reignite negotiations for Mbeumo, who is keen to make the move to Old Trafford.
Ruben Amorim, United's new head coach, is targeting a centre-forward this summer. So far, the club's only signing is Matheus Cunha from Wolves for 62.5 million pounds.
Pre-season preparations are ramping up, with United set to face Leeds in Stockholm on Saturday at the Strawberry Arena.
A tour of the United States will follow, featuring matches against West Ham, Bournemouth, and Everton.
Alejandro Garnacho's time at Manchester United appears to be nearing an end, with the winger excluded from pre-season training as the club, under manager Ruben Amorim, reshapes their squad for the 2025-26 campaign.
Brentford have completed the signing of former Liverpool and England midfielder Jordan Henderson on a free transfer.
Botafogo are making contingency plans amid growing interest from Manchester United in their goalkeeper John Victor.
LaLiga giants Barcelona have made it abundantly clear they are not interested in paying a huge transfer for Marcus Rashford and will only take him on a loan deal.
