Unions representing up to 70,000 frontline public sector workers have warned that they will take collective action if necessary to protect their members' incomes from Government proposed cuts.
Speaking on behalf of the 24/7 Frontline Alliance, INMO General Secretary Liam Doran said the proposals on allowances, overtime and premium payments would hit frontline workers disproportionately.
Mr Doran said that could not and would not be allowed to happen.
He said there would be no extension of the Croke Park Agreement if the Government maintained that stance on cuts.
The alliance represents groups including nurses, gardaí, prison officers and other emergency staff.
It intends to research the impact of the Government's proposed cuts on individual workers, and outline it at a press conference next Tuesday.
The alliance will lobby individual TDs around the country, asking how they can justify cutting take-home pay for frontline workers.
It is also preparing a briefing note for Minister for Public Expenditure and Reform Brendan Howlin.
The group will hold a series of meetings around the country to brief members.
Mr Howlin said it is better for unions to be part of the negotiations of the new agreement rather than walk away.
He said these negotiations are different than the last ones and much more complex.
The minister said it is better for those involved to "be in the tent" in the negotiations and have an input rather than walking away.
Meanwhile, the Prison Officers' Association has warned that it will pull out of the Croke Park talks if the Government continues to pursue a strategy of cutting allowances, overtime and premium payments for frontline workers.
General Secretary John Clinton said it was grossly unfair that the people who were asked to work Sundays, bank holidays and even Christmas Day should see those payments slashed.
He described the Government position as an outright attack on all the terms and conditions it had taken 50 years to get in place and said that if that strategy remained, they would have to walk away.
Elsewhere, the union representing over 6,000 psychiatric nurses said it would not accept the proposals.
The Psychiatric Nurses Association has already decided not to take part in the current Croke Park talks process.
However, Deputy General Secretary Seamus Murphy said that if ancillary payments were cut, the union would view it as a cut in core pay and members would just not go to work.