National Advocacy Service (NAS) staff, who are in their second week of strike action, have protested outside the constituency office of the Taoiseach Simon Harris in Co Wicklow.
NAS provides assistance to more than 1,500 disabled people each year with in-person advocacy interventions in areas including housing, access to justice, health care, safeguarding and supporting in decision making.
SIPTU members employed at the service last week resumed strike action as part of a pay dispute.
The union, which represents 43 of the 48 staff members at the organisation, has accused management of failing to adhere to a Labour Court recommendation on pay and conditions.
"The reality is if the improvements recommended by the Labour Court are not implemented the future of the service is in jeopardy," said SIPTU Sector Organiser Brendan Carr.
"The terms and conditions of National Advocacy Service staff are markedly inferior to those people who carry out similar work in other agencies."
"With the announcement of the end to the HSE staff embargo the flow of staff out of the service is likely to greatly increase, this will result in thousands of vulnerable people with disabilities losing a service which is vital to their independent living," Mr Carr said.
NAS wages are set by its funder, the Citizens Information Board, which receives its funding from the Department of Social Protection.
NAS has previously said that it fully acknowledges the validity of the pay claims and stands with its employees in their pursuit of equitable wages.
As well as manning picket lines across the country, NAC staff protested outside Mr Harris' constituency office in Bray, Co Wicklow, and Minister for Social Protection Heather Humphreys' constituency office in Monaghan.
