The likely fate of the proposed new partnership deal will become clearer today after a special consultative conference being held in Dublin by SIPTU, the country's biggest union.
Support by SIPTU is considered critical if the agreement, Sustaining Progress, is to receive the backing of the Irish Congress of Trade Unions when its delegates vote on the deal next month.
SIPTU leaders are expecting a vigorous debate at today's conference in the Abbey Theatre, at which every branch in the union is to be represented.
Leaders of the union will make presentations on aspects of the agreement and take questions and comments from the floor.
Many of these are expected to be highly critical of the agreement, particularly elements such as the phasing of pay increases and the requirement to enter binding arbitration on certain areas of dispute.
SIPTU's 200,000-strong membership passed the previous partnership deal, the Programme for Prosperity and Fairness, by a 70-30 majority.
The vote is likely to be much closer this time, with leaders of the union conceding that the prospect of SIPTU support for the agreement remains in the balance.
The State's largest public sector union, IMPACT, is advising members to vote in favour of the agreement, which includes a timetable for payment of the benchmarking pay increases to public servants.
Many SIPTU activists, however, will reflect the anger felt by a number of private-sector unions, including the TEEU, the IBOA and the builders' union, BATU, which are all recommending against the deal.