Talks have begun between Aer Lingus management and SIPTU after workers in three sections at the airline rejected the company's business plan.
Acceptance of the business plan by staff is seen as a key element in the imminent privatisation of the airline.
SIPTU procedures stipulate that if any individual section rejects a proposal, even where there is an overall majority in favour, it cannot be accepted.
Sources said that workers in the three sections rejected the business plan because 'local issues' had arisen.
Union representatives are now seeking clarification from management in relation to those issues.
It is hoped that that clarification will allow the ballot to be concluded.
Meanwhile, counting of a separate ballot by the Irish Congress of Trade Unions on measures to fund the employee share stake in the airline has been suspended until tomorrow.
The deadline for acceptance of those measures is Thursday.
