Eric Griffiths resigned his seat in Aberystwyth last month
The mayor of Aberystwyth has resigned after she was rejected by the Liberal Democrats as a candidate for a Ceredigion Council by-election.
Lorrae Jones-Southgate, one of four town councillors representing the Rheidol ward, was bidding to become the seat's county councillor as well.
She said she felt dejected and humiliated after being turned down by the Liberal Democrats' local branch.
A party spokesman said it had gone through the normal selection process.
Eric Griffiths resigned last month as county councillor for the Rheidol ward after receiving a police caution for a "sexual offence".
Ms Jones-Southgate said she had represented the ward on the town council for four years.
"After great deliberation I felt I could not do my job as a town councillor and as mayor knowing that the party was not behind me," Ms Jones-Southgate said.
"The decision not to select me left me in an impossible situation, and I obviously don't have the backing of my local branch.
"I feel a great deal of dejection and humiliation."
She added it had been a "great privilege" to serve as Aberystwyth's mayor, a position she was re-elected to just two weeks ago.
Ceredig Davies, leader of the Liberal Democrats on Ceredigion Council, said he knew Ms Jones-Southgate was disappointed.
"The decision was taken by the local branch and we went through due process," said Mr Davies.
"Candidates were put forward for a selection meeting and then there was a secret ballot.
"I know she was very disappointed."
The by-election will be held on 10 July.