A source close to the player has told the Hull Daily Mail that Campbell is "getting confused" by the ongoing speculation regarding his future.
He also confirmed the Sunderland have now made their first move to hijack City's record-breaking £6m swoop after sounding out Campbell's representatives.
The Manchester United striker returns to England this morning after the climax of the European under-21s Championships last night.
City had hoped their £1m-a-year contract offer was all-but a formality before the Black Cats came in with their late interest. Blackburn have also made a tentative enquiry about the possibility of landing the Huddersfield-born frontman, but he is not keen on a switch to Lancashire.