One of Northern Ireland's best-known export success stories is facing the risk of industrial action among its 530 staff.
Trade union Unite said it would be balloting members at Wrightbus in Ballymena for industrial action after the union said it rejected the company's latest wage offer.
A union spokesman said the ballot would start on February 1 with counting to take place on February 15.
Unite regional officer Davy Edmont said: "While regrettable, members have been left with no alternative but to seek a ballot for industrial action."
The union said members had rejected three pay offers from the company, claiming that shop stewards "made the members' aspirations clear from the start of the negotiation process".
Mr Edmont added: "I am available at any time to continue negotiations with the company in the hope of avoiding a dispute.
"However, our members have made their feelings known and we fully support their claim and their right to take industrial action."
No representative from Wrightbus was available for comment.
The company employs 990 staff.