Rishi Sunak has put aside party politics to fight to retain services at Darlington Memorial Hospital.
Mr Sunak, a Conservative, has joined forces with Darlington Labour MP Jenny Chapman to oppose potential downgrading of the hospital.
The two MPs believe a health service review underway in the area could lead to all specialist and emergency hospital services being concentrated on Teesside.
Proposals to changes hospital services in southern County Durham and the Tees Valley are due to be published later this year. The changes could result in the Darlington hospital losing a number of services including consultant-led maternity services and A&E.
The review is one of dozens of sustainability and transformation plans (STPs) being drawn up by health chiefs around the country.
NHS England asked commissioners and providers to work together to develop STPs as improvement plans for their area and to work with local authorities and other partners to deliver these.
In the draft STP for the southern County Durham, Darlington, Tees Valley and northern North Yorkshire areas either Darlington or North Tees hospital would lose their current status and be downgraded.
The James Cook University Hospital at Middlesbrough would retain its status as the main regional hospital dealing with emergencies and trauma. Either Darlington or North Tees hospital would be the second emergency hospital for the region.
The Friarage Hospital at Northallerton is largely unaffected by the proposals.
Mr Sunak said the Memorial, although outside his constituency, was used by many of his constituents, particularly in north Richmondshire and the Yorkshire Dales. Removal of emergency services from the Darlington hospital would mean unacceptable travel distances.
He said: “I am pleased to work with Jenny to protect services which are highly valued by many of my Richmond constituents and the people of Darlington.
“Downgrading the Memorial would mean all our emergency hospital services being located at James Cook University Hospital and North Tees General Hospitals which are barely seven miles apart. How does that make sense?
“Tens of thousands of patients would be faced with journey times of up to an hour and a half. We need to retain a specialist emergency hospital serving the western end of this vast rural area and I believe that hospital should be Darlington Memorial.
“A return journey of over three hours is surely not compatible with the NHS’s ambition of moving healthcare closer to home,” he added.
Ms Chapman has campaigned to protect the Memorial Hospital since rumours of the changes emerged last summer. She has been active in the Save our Services Darlington Memorial Hospital group and been critical of the way health chiefs have handled the review process.
Ms Chapman welcomed Rishi’s support for the Memorial. She said: “Rishi and I are united in condemning any plans which would make accessing healthcare more dangerous, inconvenient and difficult for patients and their families.
“We will fight any plans to downgrade the Memorial because we know how valuable these services are to families across Darlington and beyond.”