A ballot for protective industrial action by Siptu workers at Aer Lingus will close this evening, with results expected late tomorrow afternoon.
Up to 2,500 workers have been balloting during the past two weeks over the State airline's radical restructuring plan.
Airline unions are fighting for one of the highest pay-off deals in the State - nine weeks of pay for every year served at the company, for the 1,325 affected workers at Dublin, Cork and Shannon airports.
Aer Lingus management has proposed a three-year plan to move the state airline to a low-fares carrier. The restructuring will see almost a quarter of the workforce leave the airline.
Siptu national industrial secretary Mr Michael Halpenny has said the first priority is to ensure all change at the airline takes place by agreement.
The ballot at Siptu's branch office in Dublin airport closes this evening. The results are expected to be announced tomorrow evening.