Three senior councillors have resigned following a critical report into local special educational needs and disabilities services (SEND).
Ofsted and the Care Quality Commission (CQC) said the system in Suffolk "has not worked well for a long time".
Suffolk County Council said Rachel Hood, James Reeder and Chris Chambers had left their cabinet posts.
In a joint letter, they said their roles had "become a distraction" from the council's "vital work".
One of their Conservative colleagues, Sam Murray, was earlier suspended after calling for a "resignation or sacking".
Mr Reeder was cabinet member for children and young people's services; Ms Hood was cabinet member for education, SEND and skills; and Chris Chambers was deputy cabinet member for SEND.
"The recent Ofsted report is extraordinarily disappointing, despite Ofsted and the Department for Education's recognition of improvements in the service," the three Tories said.
"We are determined that the council will go further and faster in providing SEND children and their families with the outcomes, and positive experience, they need and deserve."
The councillors insisted that "under our leadership the service has been successfully restructured" and "significant improvements have been made".
A council spokesperson said the three members chose to resign from their roles.
The joint CQC and Ofsted report, published on Tuesday, said too many children with SEND "get lost in the system and fall through the cracks".
The council's executive director of people services, and director of children and young people, both left the local authority late last year.
Tory councillor Ms Murray, who is not a cabinet member in the administration, said her own child who received SEND provision had been "let down" by the local authority.
She was later suspended by her party.
The council said, together with its health partners, it was setting up a new SEND accountability board with an independent chair, and said a restructure was under way of children's services senior leadership.
Its chief executive Nicola Beach said: "Given the known challenges facing our children and young people services, both in Suffolk and nationally, I am taking this opportunity to restructure the senior leadership."
There would be a new management structure and the "imminent recruitment" of a new executive director, a spokesperson added.
Matthew Hicks, Suffolk County Council's leader, said: "I would like to thank Rachel, James and Chris for their personal commitment and hard work over the past two and half years.
"They have shown huge dedication to improving SEND services.
"I would like to reiterate Suffolk County Council's absolute commitment to ensuring more young people and their families receive the support they need and deserve."