Bruce would like to bring in Hart in a loan deal as regular No. 1 Craig Gordon is out with injury and Martin Fulop is closing in on a switch to Ipswich Town.
“We’ve asked the question of City and we now just have to wait and see what they say,” Bruce told the Sunderland Echo.
“But the timetable is not up to us on when we get an answer, it’s up to them.
“With these new 25-man squad rules, clubs don’t have to name their confirmed squads until the end of August, so if they wanted to, City could delay any decisions on their squad until then.”
