The Association of Garda Sergeants and Inspectors has voted to reject the latest public sector pay deal.
52.6% of members voted against the measures of the Lansdowne Road Agreement in a nationwide ballot.
The agreement has already been ratified by a majority of public sector unions, and legislation to enforce it will be introduced to the Dáil next week.
The association will discuss its response to the vote at a meeting of its national executive next Thursday.
Meanwhile the Teachers Union of Ireland (TUI) say that the Lansdowne Road Agreement fails to address the issues facing the education system.
TUI members voted 92% in favour of rejecting the deal.
They say that secondary and third level institutions have been hit by budget cuts while dealing with higher student numbers.
President of the TUI Gerry Quinn says that the increased workload is affecting the quality of education:
