Accident and emergency services in Nottinghamshire will be able to cope despite plans to downgrade an existing unit in Newark, NHS managers have said.
A 90-day consultation is under way to look at the options.
The union Unison said the changes will put extra pressure on already stretched facilities at the Queen's Medical Centre (QMC) in Nottingham.
A QMC spokesman said meeting the demand will be "very challenging" but added the hospital will cope.
Martin Benn, from Unison, said: "These are the people who need emergency treatment and face a 25-mile drive to get that emergency treatment."
"The mantra of the health service is we have to do more and more work and see more and patients with less and less resources."
We are here for people that need us and we will deliver that service
Neil Sturrock, QMC clinical director
QMC clinical director Neil Sturrock said: "There are many other places that patients can get the treatment they need.
"We are here for people that need us and we will deliver that service but there may be other options that they can try."
Matt Youdale, from the Nottinghamshire County NHS Trust, said Newark's A & E department is not closing but may be downgraded.
He urged the public to use the consultation period to express their opinions.
The Newark's accident and emergency department would be replaced with a minor injuries unit under the current proposals.
Mr Sturrock said specialist treatment could be better provided at larger centres.
More than 1,800 people have already signed a petition to save the unit.