A trade union alliance against Croke Park II has called for talks with its own negotiators amid further signs of a damaging split.
As the Government hopes to strike a deal to ease repayment costs for the IMF-EU bailout, Congress executives are facing demands to sit down with their own members.
The Alliance of Unions for a No Vote warned it would not be bound by the umbrella trade union body on the controversial pay deal.
Liam Doran, general secretary of the Irish Nurses and Midwives Organisation (INMO), one of the No unions, said it was ironic the alliance met on the day that a former International Monetary Fund mission chief warned austerity is not working.
Mr Doran said: "We have had that very strong admission today from one of the main architects of the austerity programme for this country that it cannot work. It's a pity it took the IMF so long to realise that fact. That is fully consistent with the position Congress has articulated for the last four years and that is one of the things we want to talk to them about and indeed to talk to the Government about."
Ashoka Mody, former IMF chief, said that bondholders - the international money lenders which offers funding for governments and banks - should have borne some of the cost of Ireland's financial meltdown. The alliance believes it represents 100,000 public sector workers.
Brendan Howlin, Minister for Public Expendture and Reform, hit out at unions amid suggestions that a No vote will not mean any consequences.
He said: "It is simply dishonest to say that there are no consequences arising from a No vote. The reality is that the consequences are real and have wider implications for the Irish economy. The No unions are only offering uncertainty to public servants.
"A Yes vote offers certainty and protection for public servants and a backdrop by which the state can continue its path to recovery. After all, these proposals protect the core pay of 87% of public servants in a fair and balanced set of proposals."
The alliance - including the INMO, the Irish Medical Organisation, the Civil and Public Services Union and Unite - called for talks with Congress after discussing their No stance with representatives from the Association of Secondary Teachers of Ireland, the Teachers Union of Ireland and the Association of Higher Civil and Public Servants. The Irish Federation of University Teachers is also understood to have lent its support.