Council leaders in Wales are calling for urgent talks with First Minister Carwyn Jones to put forward alternative proposals for reorganisation.
The Williams Commission last week recommended merging councils to reduce numbers from 22 to between 10 and 12.
The Welsh Local Government Association (WLGA) said it wanted to set up a task force to carry out a "pragmatic examination of existing boundaries".
The Welsh government has been asked, but is not expected to comment now.
Council leaders met in Cardiff on Friday for the first time since the commission reported.
The WLGA also said a "properly costed financial analysis" was needed, but council leaders accepted that changes would happen.
A statement said council leaders wanted to "test the parameters of alternative proposals" to the commission's recommendations.
The statement continued: "...we will fully explore an alternative set of proposals which are pragmatic, examine existing boundaries and set out a properly costed detailed financial analysis, which is not contained in the commission's report.
"The WLGA and our local authorities will immediately set up a task force to do this and will produce an analysis on public services reform."
The association's chief executive, Steve Thomas, told BBC Wales that local authorities wanted to play a full part in the "big debate" on the future of public services.
"They want urgent discussions with the first minister, they want to know what the timescales for reform will be," he said.
"We ourselves would like to put a compelling case to the first minister for change in local government, and we'd like that to be considered.
"It will flow from an analysis that local government itself will undertake, particularly looking at costs and looking at boundaries, but also looking at the best fit for our communities across Wales."
The report by former NHS Wales chief executive Paul Williams concluded, as a minimum, that the following local authorities should merge:
- Isle of Anglesey and Gwynedd
- Conwy and Denbighshire
- Flintshire and Wrexham
- Ceredigion and Pembrokeshire
- Neath Port Talbot and Bridgend
- Rhondda Cynon Taf and Merthyr Tydfil
- Cardiff and the Vale of Glamorgan
- Blaenau Gwent, Caerphilly and Torfaen
- Monmouthshire and Newport
With Carmarthenshire, Powys and Swansea unchanged, this would leave 12 authorities.
Mr Jones is expected to begin meeting assembly opposition party leaders next week, in an effort to reach cross-party agreement on the reorganisation.