The Red Devils are preparing for a busy summer transfer window and a new playmaker is reportedly one of the main priorities for manager Ruben Amorim.
Amorim is a huge admirer of Cunha and Ornstein has acknowledged that the 25-year-old also 'wants to join' United ahead of next season.
United still need to agree on personal terms as well as trigger the £62.5 million release clause in his contract when it becomes active.
As things stand, United are clear favourites to land the former Atletico man, who has apparently turned down interest from Newcastle United.
Arsenal were heavily linked with the playmaker at the start of the year, but they have decided to pursue alternative targets for the summer.
Chelsea have also been credited with an interest, but Cunha seems convinced about joining the revamped project under Amorim.