SIPTU delegates voted overwhelmingly to enter talks on a new national agreement, following an impassioned three-hour debate at the union's biennial conference in Killarney.
Despite strong speeches opposing social partnership, only eight delegates voted against the main national executive motion.
Ms Nuala Keher, an executive member who described herself as "a contract worker with no pension", said she supported the motion to enter talks because she believed unions should "stay at the national bargaining table. I do not want them to run off into the free collective jungle and leave the weak to fend for themselves."
Even if there was no national agreement she called on the trade union movement to make a "collective response" to the crisis that would follow. "Call it what you will. I call it standing together. I call it trade unionism," she said.
Ms Carolann Duggan from Waterford, who has stood three times for national office in SIPTU on an anti-partnership policy, said trade unionists were being asked to deal "with gangsters".
"The crooks, the thieves and criminals in this society are not the workers dragged off picket lines and put in Mountjoy," she said.
However, the chairman of SIPTU's construction branch, Mr Michael Finnegan, said that while a lot was wrong with Partnership 2000, including low pay rises for building workers in an industry making millions, there was nothing wrong with the idea itself. "We've been on strike and we know what it's like. It's not always the answer, or being revolutionary.
"Being revolutionary is seeing kids in Ballyfermot coming out of school able to read and write and enjoy a quality of life they haven't had before." If workers wanted an input into areas such as health, education or housing they needed a national agreement, he said.
The chairman of the health services branch, Mr Jack Kelly, said agreements could be made to work for trade unionists, provided they "did not go to sleep. We worked the agreements hard and secured significant benefits.
"Domestics whom we represent had a pay level of £137 a week in 1987. We managed to increase that to £252 a week in 1999." He said that was an increase of 84 per cent at a time when prices rose by 30 per cent. "This story can be repeated right throughout the health sector," he said.
SIPTU's regional secretary for the midlands and south-east, Mr Jack O'Connor, said the trade union movement had arrived at a defining moment. The old national model of national agreements forged against the background of mass unemployment and crisis in the public finances had been confronted.
"Angst and anger are well justified, but delegates should never allow them to be a substitute for policy and strategy," he said.
"History does not offer any evidence to support the view that a return to old-style free collective bargaining, or street agitation for that matter, will provide better, fairer or more equitable results."
SIPTU's regional organiser for Dublin's private sector, Mr Jack Nash, said "a new national agreement will not come cheap". He called for trade union recognition to be "put on the statute book" and said workers should receive "an Ansbacher bonus".
The Taoiseach welcomed the decision of the State's largest trade union, SIPTU, to enter discussions on a new social partnership programme, adds Kevin Rafter.
Mr Ahern said last night that the membership of SIPTU was "obviously aware of the benefits that have accrued to them from previous national programmes".
In a comment aimed at the nursing unions ahead of their threatened industrial dispute, the Taoiseach said the SIPTU vote should "convince others to consider in a positive way their commitment to continued social partnership".