Council leaders in Monmouthshire have unanimously backed campaigning against six post offices closing.
Map showing the six village post offices
Post Office Ltd is consulting on a series of closures across Newport, the Gwent valleys and in Monmouthshire.
But Monmouthshire's council cabinet have warned that the six earmarked in the county provide vital services, especially for the elderly.
"We must do everything in out power to keep them open," said Cllr Brian Hood, the council's older peoples' champion.
He added: "The social benefits provided by rural post offices would cost the council a small fortune to provide."
The threatened post offices are at Govilon, Llanellen, Mathern, Sudbrook, Tintern and Devauden, which will be closed completely or replaced by a mobile service.
The council cabinet said it is now asking for Post Office Ltd to meet elected members in those areas affected.
Leaders are also writing to the assembly government urging it to step in and provide financial assistance for those offices facing the axe.
Announcing the list of local offices earmarked for closure last month, Post Office Ltd said closing any branch was always very difficult.
Steve Geraty, network development manager for Wales, said the area between Newport, the Gwent valleys and rural Monmouthshire was "diverse in nature".
But he stated that 63 branches would remain in rural areas, where 48% of the population live.
He added that the company had given consideration to the needs of those living in "communities defined as deprived".