Two district councils in Buckinghamshire have threatened to take legal action in a bid to prevent the creation of a single unitary authority.
Buckinghamshire CC, together with Aylesbury Vale, Chiltern, South Buckinghamshire and Wycombe DCs, are due to be merged into a new unitary in 2020.
However, the plan has been rejected by all four district councils, meaning housing and communities secretary James Brokenshire must legislate for the merger by the end of March.
In a joint statement, Isobel Darby, leader of Chiltern DC and Katrina Wood, leader of Wycombe DC, said they had written to Mr Brokenshire as a “preliminary step” to legal proceedings.
They said they had taken the move with “great reluctance” but felt that the Ministry of Housing, Communities and Local Government had left them with no alternative.
“We believe that it is in the best interests of our communities in Buckinghamshire to challenge the process being used,” they said.
“Our aim is not to hinder the creation of the new council but to ensure we get an excellent, new council, giving us the opportunity to start afresh and form a council that serves our residents and businesses well, and one we can be proud of.”