It is understood moves are afoot to create one chief executive for North Tees and Hartlepool NHS Trust and South Tees Hospitals NHS Trust.
The last inspection of South Tees by the Care Quality Commission (CQC) found it required improvement in July 2019 – with the watchdog set to return next year.
It has also faced long-standing financial headaches – not helped by a Private Finance Initiative (PFI) deal now costing the trust more than £1million a week.
Meanwhile, North Tees and Hartlepool was rated a “good” trust by the CQC in its latest 2018 inspection.
The two NHS bodies are Teesside’s largest employers – with almost 15,000 staff between them.
A meeting was due to take place on Wednesday, December 1, between Hartlepool council leader Shane Moore, Stockon council leader Bob Cook, and Professor Derek Bell, the joint chairman of South Tees and North Tees and Hartlepool council of governors.
Others are understood to be taking part in the meeting.
Stockton North MP Alex Cunningham has written to Health Minister Edward Argar with his concerns.
He has also penned a letter to Professor Bell.
Cllr Moore said he had concerns about what he’d heard so far – and agreed with Mr Cunningham about the state of finances at South Tees.
He said: “South Tees has been performing poorly while North Tees and Hartlepool is doing very well.
“It’s in a good financial position and has cut its cloth accordingly.
“That’s our concern – hence us calling this meeting tomorrow to try and establish the facts around what’s going on.”
Like Mr Cunningham, the independent council leader said he was for collaboration between the two trusts.
However, he shared doubts about merger moves – later adding he would fight them “tooth and nail”.
Cllr Moore said: “I think we (the council) have had a really good relationship with the trust because it’s been a bit rocky in the recent past.
“We’re all for collaboration – but that does not extend to sharing a bank account.
“We all want the same level of healthcare across the system – but we don’t want to sacrifice a good level of healthcare in a race to the bottom.
“We want to establish the facts tomorrow, see exactly what’s going on, and why this is being proposed from certain quarters.”
A joint statement from both Teesside trusts said the NHS had faced huge challenges in recent years.
But it didn’t shed much light on the possible job merger.
The statement added: “Throughout this time, both Tees trusts have remained dedicated to the provision of services that reflect the aspirations of the communities we serve.
“This collaborative dedication involves a number of key health and care providers, partner agencies and our local authorities.
“To this end, we appointed a joint chair for North Tees and Hartlepool and South Tees Hospitals so that our expectations could be realised with true collaboration across Tees Valley and North Yorkshire.
“Our population health plans focused on tackling health inequalities and improving outcomes for our local communities cannot and will not be realised by our organisations alone.
“The reality for our region is that we must commit wholeheartedly to transparent collaboration.”