Critical care at the Friarage Hospital will be suspended from 27 March, with only patients with more minor illnesses and injuries to be treated at the Northallerton site from this date.
This means around 10 per cent of A&E patients currently treated in the town will be taken to James Cook Hospital in Middlesbrough or Darlington Memorial Hospital, both around 30 minutes away by car.
South Tees Hospitals NHS Foundation Trust, which runs the Friarage and James Cook, said it had been trying and failing to tackle gaps in the workforce at the Friarage and that it did not have enough consultants to be safe.
But in a lengthy statement released today, Richmond MP Rishi Sunak said the announcement was "very frustrating" as "the recruitment and staffing issues underlying this unwelcome change have been known about for a long time".
He added: "Indeed, I have been pressing the trust on this specific issue for well over a year, following a meeting I organised with local medical staff in 2017 to discuss recruitment in detail.
"What is clear is that the issue here is not money, but persuading a handful of relevant critical care and anaesthesia doctors to work at the Friarage."
Mr Sunak said the Friarage has historically been staffed with more general, rather than specialist, consultants who are now retiring, and it was proving hard to persuade their counterparts at James Cook hospital to move across.
He said this was due in part to changes in clinical guidance from the Royal College of Emergency Medicine which requires more specialist emergency care consultants to work in critical care wards.
And he said specialist critical care doctors prefer to work at larger hospitals like James Cook where there is much higher activity in their chosen specialty, compared to the very low volumes at the Friarage.
He said in his statement: "As many of you have suggested to me, I have consistently pushed the Trust to find ways to share these doctors permanently across both the James Cook and Friarage sites, given that they are part of the same trust.
"I have been told that the doctors have been offered substantial incentives to work at the Friarage permanently but have chosen not to accept. I have also been told that there is no way the Trust can contractually roster these doctors to work permanently across both sites."
A public consultation will begin later on the hospital's long-term future, but Mr Sunak said if it became permanent he would argue for as much additional work to be done at the Friarage as possible.
He added: "I am talking to the Yorkshire Ambulance Service about issues around the safe transport of critically-ill patients to the James Cook from the more remote parts of the constituency, like the Dales."
South Tees Hospitals NHS Foundation Trust said in a statement: "We have worked with our anaesthetic consultants at both the Friarage and James Cook hospitals and have explored every avenue with them in order to resolve our workforce issues and maintain critical services at both hospitals.
"However, the workforce problems we have in recruiting anaesthetists are local, regional and national. Nationally only 42 per cent of training spaces are filled for anaesthetists, as medical students choose to train in other disciplines.
"Locally, there are fewer doctors with generalist skills, as training becomes more specialised, resulting in fewer doctors available with the necessary skills to work at smaller hospitals, like the Friarage."