One of the two Conservative ward councillors for Headcorn has resigned.
Shellina Prendergast has quit the borough council, leaving Martin Round as the ward's sole representative.
A by-election will be held, but no date has yet been set.
Mrs Prendergast had been a councillor since May 2016, and left on July 2.
She remains a Kent County Councillor representing Maidstone Rural East Division, where she is also a cabinet member. She is also a deputy chairman of the Faversham and Mid Kent branch of the Conservative Party.
She said: "It is with regret that I have submitted my resignation from Maidstone council. This decision was not taken lightly, and my motives are purely in the interests of those residents I represent at both borough and county level.
"Having worked as a 'twin-hatter' for more than a year now, it has become clear to me that the ward deserves to have three voices fighting its corner rather than the two it has currently.
"Headcorn falls within my Kent County Council Division of Maidstone Rural East, and I will continue to represent residents where I feel I can facilitate the best outcomes for those who have given me a mandate to represent them."
Maidstone council leader Martin Cox (Lib Dem) said: "Shellina was a very dedicated councillor who liked to give 100%. It can be difficult trying to do both a county and borough role and I know she would have been disappointed if she weren't giving her all."
Mrs Prendergast had attended only 13 of the 18 borough meetings that she was due to attend so far this year.