Police have been called in to investigate an alleged altercation between a Liberal Democrat election candidate and another party member in Warwickshire.
The incident took place during a branch meeting in the Nuneaton Abbey ward in the run-up to the county council elections.
It has led to Brian Verden, the branch's membership secretary, urging voters not to vote for the party's candidate in the ward, Ashrif Pathan.
Mr Pathan denies Mr Verden's claims.
News of the alleged altercation is likely to cause embarrassment for the party on the eve of the elections and could affect its prospects in the ward.
Liberal Democrat central office in London warned Mr Verden risked being thrown out of the party if he was found to have brought it into disrepute.
It is conducting its own investigation into the incident but said no action would be taken until after the elections and while police inquiries were continuing.
Mr Verden, aged 67, a licensed officer with Coventry Cathedral, claimed he needed hospital treatment after the incident at the Chilvers Coton Liberal Club in Nuneaton.
The disagreement erupted over the number of campaign leaflets needed for the election.
But Mr Pathan, a 39-year- old carer from Nuneaton, denied Mr Verden's claims and claimed Mr Verden had attempted to influence decisions that were outside his remit as membership secretary.
David Allworthy, the Lib Dems' head of compliance and constituency support, said: "My understanding is the investigation is on-going.
"We won't attempt to finalise the disciplinary process until the police have let us know if they are going to press charges."
But on Mr Verden's public condemnation of his party's candidate, Mr Allworthy added; "That would be a breach of the party's rules. If the investigating party decide it requires disciplinary action then it will be taken."
No one was available from Warwickshire Police to comment on the inquiry.
