Trade unions must ensure they receive a fairer slice of the cake from any future national agreements, IMPACT president Mr Bill Gallagher told delegates to the annual conference in Bundoran, Co Donegal.
He also argued against tax cuts that would result in poorer public services and called for the provision of more local authority accommodation to help tackle the housing crisis.
IMPACT is the State's largest public sector union, representing 35,000 administrative, technical, professional and clerical workers.
Mr Gallagher was outlining the union's stance on pay and taxation at the opening session of the conference last night.
On national agreements, he said: "It's a fact that our members have enjoyed real improvements in after-tax incomes, well ahead of inflation. But Partnership 2000 was based on economic predictions that turned out to be far too pessimistic."
While workers had "demonstrated great discipline, company profits have soared and the Exchequer rakes in the cash," he said.
"I wonder if it's time for the trade union movement to start developing its own capacity to make economic predictions and forecasts. Then we can take a more informed view of the information given to us and ensure a fair slice of the cake when we enter national agreements," he said.
He acknowledged that agreements had given unions influence on a wide range of Government policies, "from tax reform and employment to union recognition and equality".
"Where else in Europe," he asked, "would a PD employment Minister be compelled to introduce a national minimum wage?"
He reiterated the union's commitment to make flat-rate increases for the low-paid part of any successor to Partnership 2000.
Mr Gallagher also warned the Government that the "uneven outcomes" of restructuring deals within the public service, under the Programme for Competitiveness and Work, had "left a bad taste in the mouth" for many public servants.
He refrained from mentioning the headline-setting claim of the nurses, possibly because many public health nurses are IMPACT members.
Turning to the provision of public services, Mr Gallagher said: "You can't maintain a state-of-the-art economy on the basis of sticking-plaster services. Irish workers have contributed more than anyone to the economic miracle that is modern Ireland."
He added: "We're in the middle of Ireland's most serious housing crisis but local authority housing is virtually non-existent. "We have the highest growth rate in the European Union but we're at the back of the queue when it comes to health services, and the queue is getting longer and longer," he said.
"Our cultural and heritage services are neglected and our roads and public transport are an international embarrassment. While we are fighting for tax breaks for child-care costs, our colleagues in Scandinavia have high-quality services provided free by the state."
If there was to be a new national agreement, "it must deliver the range and quality of services our people need, services that public servants can be proud to stand over," he said.