Pembrokeshire council is to start talks about merging services with a neighbouring authority.
Leader Jamie Adams says he does not believe reorganisation is necessary but expects it will be forced on councils by the Welsh government.
Ministers have signalled they want the number of councils in Wales to drop from 22 to 10 or 12, as recommended by the Williams Commission.
In a statement earlier this month, new Public Services Minister Leighton Andrews said councils should consider mergers to "shape their own reform".
Pembrokeshire council leader Mr Adams said: "It is now clear that Welsh government intend to legislate to force reorganisation upon us.
"While I do not agree that local government reorganisation is necessary, it would be foolish to ignore the fact that it is likely to happen.
"I understand that Ceredigion councillors are opposed to a merger, and I respect their point of view. However, I do not think this is an issue that we can, or should, ignore."
He is setting up a cross-party working group of councillors to "consider the merits of a voluntary merger with Ceredigion County Council".
But last week, Ceredigion council leader Ellen ap Gwynn said a "business case does not exist to support a merger between Ceredigion and Pembrokeshire".
However, Conwy and Denbighshire are examining their options.