Proposed changes to the way health services are delivered have put the re-start on work at the Midland Metropolitan Hospital under threat.
The hospital is around two-thirds built but no work has been done on it since the collapse of Carillion more than a year ago.
Frustrated Sandwell NHS trust boss Toby Lewis said he had "grave concerns" around potential changes to clinical commissioning boundaries which could split Sandwell from neighbouring West Birmingham.
The boundaries control where GPs refer patients to and there are concerns the changes could impact on services at the Midland Met, being built in Sandwell.
It was hoped a new contractor would be named in the summer complete the work on the hospital. Balfour Beatty has been doing early works since October.
The Sandwell and West Birmingham NHS Trust is due to sign off on the re-start of the Midland Met next month but uncertainty over the boundaries could cause complications.
In a a report to trust board members, Mr Lewis said: "It remains our strong view that any such hard border proposal is a red rated risk to the coherence of the Midland Metropolitan Hospital business case.
"This is because such a division of responsibility will necessarily drive divergent clinical pathways for the same population using the site.
"The timing of this debate is problematic, with the Midland Met final business case due back for approval at the May board, which is the latest possible date on which the extant build programme can be maintained.
"As such the trust will write now to GP colleagues and statutory partners setting out our grave concerns, which are widely known, and the risks created by the continued uncertainty. The position is clearly a very disappointing one, given the ostensive commitment of partners to the delayed completion of the site."
Mr Lewis told the Express & Star: "Finishing the process of choosing a contractor requires approval of a preferred bidder and then permission to sign a contract. Each requires approval by the trust’s board. This is due to happen later in June and in early July.
“We are committed to Midland Met opening in 2022. We believe we had the conditions in place to do so, and hope that we retain partners’ support to move forward at pace.”