Tram workers in Edinburgh are being balloted on industrial action.
Services over the Christmas and New Year period could be hit if workers vote in favour of action, according to the union Unite.
It claims its members fear for their jobs because of a "damaging culture of blame" within the organisation.
Edinburgh Trams said it was disappointed Unite was taking the move before "exhausting internal processes to resolve their concerns".
The union also claims alleged disciplinary action taken against some of its members has been "unreasonable and unjust" but the tram firm says it has confidence in its disciplinary policy.
Workers have until 26 November to return their ballot papers, with a consultative vote earlier showing 83% in favour of taking action.
Unite said it anticipates any industrial action will take place in the run-up and over the Christmas and New Year period.
'Consistently and fairly'
Both sides are scheduled to have talks at the conciliation service Acas on Thursday in a bid to end the dispute.
Unite regional officer Lyn Turner called on trams bosses to approach these in a "positive manner".
He said: "The strength of support for an industrial action ballot was rock-solid.
"The public of Edinburgh should know the reality here, which is that senior management at Edinburgh Trams have so far refused to engage with Unite on the legitimate concerns we have over the damaging and hostile culture which exists."
Mr Turner added: "Talks with Acas are scheduled to hopefully resolve this dispute but that will only happen if Edinburgh Trams management approach them in a positive manner which until now they have not."
An Edinburgh Trams spokesman said: "We are once again disappointed that Unite have decide to take this action without exhausting internal processes to resolve their concerns.
"We are confident our disciplinary policy is in accordance with the Acas Code of Conduct and is applied both consistently and fairly.
"However, our communication channels remain open ahead of our meeting with Unite on 8 November where we hope to fully understand their objectives."