Both said they were acting because of financial constraints, but they had also been prominent in a failed campaign for an autonomous all-Wales local government association, completely independent of the Local Government Association.
Mr Davies wrote to both councils just before Christmas asking them to reconsider their decision.
Cardiff deputy leader Gordon Houlston has now revealed that the council was already discussing the possibility of signing up to the WLGA. 'In my view, there is more than a 50:50 chance that we will be coming back in,' he said.
'I believe the association would be stronger with all local authorities in membership,' Mr Middlehurst said. The purpose of the meeting was to make contact and to 'explore the areas of concern the councils may still have'.
In his letters, Mr Davies referred to a partnership agreement between Welsh local and central government signed just before Christmas. He views this as setting the tone for the relationship between councils and the Welsh assembly.
'The signing of the framework presents your council with an opportunity to review its decision to stay outside the WLGA,' he wrote. 'I firmly believe it would be in everyone's interest if your council, through the WLGA, joined the central/local government partnership committed to furthering the economic and social development of Wales.'