The General Secretary of IMPACT has warned that there will be "unrelenting pressure" to erode public services, wages and working conditions until the country's financial position improves significantly.
Shay Cody was addressing delegates at the conference of the country's biggest public service trade union in Killarney, Co Kerry.
The Croke Park Agreement was the deal struck between the Government and unions to manage change in the public service.
It is approaching mid-term in the agreement and already the number of public servants - many of them IMPACT members - has been cut by 20,000.
IMPACT, which represents 63,000 members, is putting its faith in the Croke Park Agreement to manage that public service change in a way that avoids compulsory redundancies and further cuts to public servants' salaries.
Mr Cody described the agreement as a valuable protection for his members.
He said they regarded it as better than what is on offer to public servants in Greece, Spain, Italy and Portugal.
The next battle is already looming in the background at the conference.
Public servants are paid €1.5bn every year through 800 different allowances.
But the Government has told public service unions it wants to cut that figure by €75m, and that plan is likely to face considerable resistance.