The Association of Higher Civil and Public Servants has recommended the acceptance of the public sector pay-and-reform deal.
The executive of the union, which represents over 3,000 senior civil servants and managers, says the offer is the best hope of ensuring no further cuts in the public sector.
However, it comes as the Unite trade union earlier recommended the rejection of the deal, while IMPACT and two of the teachers unions, the ASTI and the TUI, have already recommended a no vote to their members.
It has prompted fears that the pay-and-reform deal is in danger of collapsing.
Regional Secretary with Unite Jimmy Kelly has said workers are "in no mood to co-operate".