The proposed public service agreement "Building Momentum" is almost certain to be formally ratified next Tuesday after the Irish Nurses and Midwives Organisation overwhelmingly endorsed the deal by a margin of 95%.
The vote by the INMO's 40,000 members boosts ratification prospects because three of the four largest public service unions, the INMO, SIPTU and the INTO, have now backed the agreement.
The largest public service union Fórsa is expected to deliver a similar vote on Monday.
If the deal is ratified, it will be a relief to the Government, as it will deliver certainty in pay and industrial relations for the next two years as it combats the consequences of Covid-19 and Brexit.
A spokesperson for the INMO described the ballot result as "definitive", noting that the planned reduction in working hours was of major importance to members.
He also said members were keen to see progress on pay owed to management grades following the 2019 strike.
Meanwhile, the Irish Medical Organisation voted overwhelmingly to reject "Building Momentum" by 95%.
The union, which represents consultants, non-consultant hospital doctors (NCHDs), public health doctors and community health doctors said the proposed agreement did not recognise the new health service realities brought about by the Covid-19 pandemic.
"Nor does it address the longstanding grievances of doctors working in the public health services," the union stated.
The Chairman of the IMO NCHD Committee Dr Paddy Hillery said: "Our members are exhausted, stressed and angry. This agreement doesn't live up to the challenge of this moment and our members can't support it."
He warned: "NCHDs are working excessive, illegal, and unreported hours. It is simply not sustainable and we must send a clear message to Government that it is beyond time to face up to the failed policies of the past."
The Chair of the IMO's Consultant Committee, Dr Clive Kilgallen said that since what he called the extraordinary failed policy of 2012 which imposed swingeing and unique salary cuts on consultants, they had had huge difficulties in recruiting and retaining consultants.
He said this had led directly to long waiting lists for both in-patient and out-patient care, with over 270,000 patients languishing on a waiting list to see a consultant for over twelve months.
Dr Kilgallen added: "As consultant vacancies increase patients will continue to suffer unacceptably long delays in accessing care. Successive Governments have refused to deal with the issue despite promising to do so."
Referring to a long-standing dispute involving public health doctors seeking regrading as consultants, the Chair of the IMO's Public Health Committee Dr Ina Kelly said they could not support a pay deal that did nothing to address fundamental problems.
She said: "Consultant level doctors in Public Health Medicine have been ignored and disrespected for over 20 years and despite the recommendations of numerous Government commissioned reports we are still not acknowledged and employed as consultants.
"The Covid-19 pandemic has exposed the cost to society of not resourcing a consultant-provided public health medicine service. Our members can no longer accept a mixture of piecemeal measures and forgotten reports."
The only organisations to reject the deal so far are the ASTI secondary teachers' union, the Medical Laboratory Scientists Association and the IMO.
Some unions have not yet held a ballot, including the Teachers Union of Ireland.
Certain unions and associations which are not affiliated to Congress and who negotiated through a separate strand have not yet balloted as they are seeking clarifications.
They include representatives for Garda Siochana grades, the Defence Forces enlisted and officer grades, and the Psychiatric Nurses Association.
