A House of Lords committee is to take evidence on the "practical issues" of the proposed implementation of unitary authorities in Exeter and Norwich.
The changes will give the cities responsibility for all functions of local government from road building to schools.
The Conservatives expressed fury with the government "naked opportunism" when it announced the restructuring of local government via a written answer on February 10.
Shadow communities secretary Caroline Spelman raised the issue in a point of order.
She said the changes will "force expensive and undemocratic restructuring on local government in Devon and Norfolk, and cast uncertainty over the future of the status of Suffolk".
Spelman accused the government of a u-turn, "ignoring the advice of the Boundary Commission".
The House of Lords merits committee is calling for written evidence on the practical issues of the proposed implementation of unitary authorities in Exeter and Norwich.
They will consider the accuracy of costs and benefits, whether there is sufficient time to implement the changes and whether the 'outcome of consultation' accurately represents the various views.
Written evidence must be submitted by February 22.
The proposed restructuring has proved contentious within the department for communities and local government.
Last week blogger Iain Dale reported that the department's permanent secretary, Peter Housdon, asked for a written direction from secretary of state John Denham to implement the changes.
Houdson took the unusual step in accordance with paragraph 5.5 of the ministerial code.
"Where an accounting officer of a government department considers that a minister is contemplating a course of action that would be likely to infringe financial propriety or regularity, or the accounting officer's wider responsibilities for economy, efficiency and effectiveness, it is the duty of the accounting officer to so advise the minister.
"If that advice is then overruled the accounting officer will be required to seek a written direction from the minister to enable that action to be carried out."
