Three hospital trusts are to discuss merger proposals that would create one of the largest NHS trusts.
The boards of Basildon, Southend and Broomfield hospitals in Essex will meet on Wednesday to approve the formal start of the process.
A merger would “modernise services” and make care “more reliable and safer for patients”, a consultants’ report said.
But a campaign group said the move would reduce the number of services and affect staff pay and conditions.
The three trusts have a combined financial deficit of more than £49m, according to board papers.
A new single organisation covering all three areas could be in place by April 2019.
A public consultation will run until 9 March, with a final decision to be made in the summer.
A report said research identified below-average performance in areas including cancer waiting times, patient experiences and care and support for patients with long-term conditions.
“Change has to happen to maintain the safety and quality of care in the future, and in a way that will improve outcomes for patients and support our staff,” it continued.
If approved, the new trust would serve more than 1.1 million people across Essex, employing more than 14,000 staff.
The hospitals have worked collaboratively since 2016, and are currently run by a joint executive group.
Chief executive Clare Panniker said a number of options had been tested “in a rigorous appraisal process”.
She added: “The recommended option is to work as one organisation.”
Mike Fieldhouse, secretary of Save Southend NHS, said the group was “very much opposed” to the merger.
“This would inevitably lead to a reduction in the number of services available locally to patients plus the potential implications for staff contracts, conditions and pay are huge, too,” he said.