Cumbria County Council is threatening legal action against the government over plans to create two new local authorities.
Last month it was announced that the current system of local government in the county - of one county council and six district authorities - would be replaced by two unitary bodies covering the east and west of the county.
The county council has branded the decision "unlawful" and has said it may seek a judicial review.
It has referred to a decision announced on the same day that North Yorkshire would be governed by a single unitary authority. It has pointed out that Cumbria County Council is led by Labour - the largest party, which is supported by the Liberal Democrats in a joint administration - while North Yorkshire is controlled by the Conservatives.
In a letter to Communities Secretary Robert Jenrick, the council has said:
The Cumbria Decision was unlawful in that the SoS [Secretary of State]:
a. left out of account necessarily material considerations which his own guidance requires to be taken into account;
b. failed to conscientiously consider the consultation responses of CCC [Cumbria County Council] showing why the Two Unitary Approach did not meet the SoS’s own guidance and would not deliver that which his guidance required;
c. failed to understand or apply his own guidance in terms of the required scale of the new unitary authorities and provided no reason to depart from that guidance; d. failed to recognise that the Two Unitary Approach is predicated around the creation of a mayoral combined authority to ensure co-ordination on key matters thus adding a new tier of local government administration, undermining the savings claimed and the need for which was a key reason why a Single Unitary Approach was appropriate here;
e. for no valid reason, acted inconsistently with his approach in North Yorkshire where a Single Unitary Approach was adopted – in the case of North Yorkshire factors in favour of a Single Unitary Approach were relied on but the same factors equally applicable to Cumbria were ignored in the Cumbria Decision;
f. appears could have been motivated by the possible party political advantage that splitting Cumbria in two may secure for his party. If this was a factor in the decision, it would be an abuse of power and unlawful;
g. acted irrationally; and
h. failed to provide adequate reasons addressing the principal controversial issues.
Cumbrian Conservatives have criticised the move.
Carlisle MP John Stevenson said the county council was "wasting taxpayers' money".
Liberal Democrats in the county also criticised the move and said that they do not support it.
Council Peter Thornton, who leads the Lib Dems on the authority, said: “We have just 18 months to create two new Cumbrian councils from the seven existing councils.
“The county council Liberal Democrat group believe that we should be concentrating on this task rather than expending time and money challenging the government’s decision.”
The county council has asked the government to reply to its letter by 4pm on Monday, August 23.