According to Sky Sports, the Black Cats owner has had a number of offers he is weighing up.
The reports have emerged on the eve of Pompey’s League One play-off semi-final trip to the Stadium of Light.
Kenny Jackett’s men renew their rivalry with Jack Ross’ men after already meeting three times.
The Blues delivered a 3-1 victory in League One in December, as well as the penalty shootout triumph in the Checaktrade Trophy final at Wembley in March.
Pompey picked up a 1-1 draw in Wearside two weeks ago.
Donald completed his Sunderland takeover from former owner Ellis Short last summer.