The Frontline Alliance, which represents 70,000 nurses, gardaí and other emergency workers, has announced plans for a campaign against the new Croke Park deal.
The group, which met this afternoon, says it remains vehemently opposed to the proposals now that it has seen the full detail.
Association of Garda Sergeants and Inspectors President John Redmond said the group will run a media campaign against the deal along with meetings in cities and towns around the country.
He said gardaí would "up the ante" in their work-to-rule if the Government persisted with its plans.
However, he said there would be no so-called "blue flu".
Earlier, the largest public service union, IMPACT, said it will recommend that its 63,000 members accept the new Croke Park proposals.
The decision was made at a meeting of the union's executive today.
The Public Service Executive Union which represents mid-ranking civil servants has also recommended a yes vote on the Croke Park pay proposals.
The Irish Nurses and Midwives Organisation is to recommend that its 40,000 members reject the proposals.
The proposals will be put to a nationwide ballot of nurses, despite the fact that the INMO walked out of negotiations before the talks were complete.
In a statement, the union reiterated its view that the proposals are unbalanced, unfair and hostile to a female workforce.
Three other unions had already said they will recommend rejection of the proposed deal: the Association of Higher Civil and Public Servants, the Teachers' Union of Ireland and the Irish Federation of University Teachers.
The National Executive Council of the country's largest union SIPTU will meet next week to decide its stance.
Officials of the Irish Medical Organisation, who walked out of the negotiations on Sunday night, will brief its executive on Wednesday.
The proposals are aimed at reducing the public sector pay bill by an additional €1 billion over the next three years.
They include pay cuts for top earners, additional hours for no extra pay, and reductions in allowances and premium payments.
Unions that reject deal with lose benefits
Meanwhile, Government sources remain adamant that unions which reject the proposals will lose the benefits that apply under the agreement, including the guarantee of no compulsory redundancies.
Taoiseach Enda Kenny said that agreeing the proposed Croke Park extension deal would be an international signal that Ireland was determined to fix its economic problems.
Addressing an IBEC conference in Dublin, Mr Kenny said he felt the contribution from the public sector payroll was "absolutely fair".
He said implementing these savings would be "another big step on the road to economic recovery".
Mr Kenny told the conference that the pay and pensions bill accounts for 35% of total public spending.
"In the context of the additional €3bn in spending cuts required by 2015, this contribution from payroll is absolutely fair.
Minister for Education Ruairi Quinn said that reducing the public sector pay bill was not "easy or pleasant".
However, he said the Government had to make reductions as it could not continue to borrow at the level it had been.
Mr Quinn said it was up to the unions to ask themselves what might happen if the deal was rejected, and it was up to them to see what alternatives there may or may not be.
Earlier, TUI General Secretary John MacGabhann said a growing number of the TUI's membership comprises people on very low pay and the agreement would "punish" them.
CPSU Deputy Secretary Derek Mullen said his members had nothing more to give.
He said the longer working week amounted to a 6% pay cut and the incremental freeze was another 1% or 2% cut, which was too much for workers taking home €400 a week.