SIPTU's Health Division is to begin a ballot of up to 5,000 members working in Section 39 organisations for strike action in a dispute over pay.
The union is accusing the Government of failing to honour a pay agreement struck at the Workplace Relations Commission (WRC) in October 2023.
The deal included a commitment to restore the pay link between the public sector and the community and voluntary sector.
Section 39 organisations are privately owned charities and agencies that are contracted by the State to provide healthcare services.
There is no specific reference to Section 39 workers in the Programme for Government.
However, there is a pledge to "work with the voluntary sector through industrial relations mechanisms and other processes to progress pay issues that affect the delivery of disability services and the long-term viability of organisations within the sector."
The incoming government said it will also consider measures to attract and retain staff in the disability sector, as well as developing a new workforce plan to address immediate staffing shortages and longer-term needs.
SIPTU said this pledge does not go far enough.
"Our members' patience has now run out; they are saying enough is enough and want to take action," said SIPTU Sector Organiser Damian Ginley.
"The pay link between the public sector and Section 39 Organisations must be restored, and the Government must stop treating our members, who provide essential disability care, elder care, and home support services, as second class."
"A strike may be imminent unless a swift solution can be found to this dispute," Mr Ginley said.
A pay agreement was reached with staff in the community and voluntary sector in October 2023 hours before strike action was due to commence involving 5,000 workers.
The deal included an 8% pay increase and a commitment to restore pay parity with the public sector.
The issue of pay for Section 39 workers came to the fore during the General Election campaign following an encounter between Taoiseach Simon Harris and disability worker Charlotte Fallon in Kanturk, Co Cork.
