An emergency motion calling for Government to make an "immediate and major intervention" to protect Tara Mines will be debated at the ICTU conference today.
It comes as a second day of talks between unions and Tara Mines management at the workplace relations commission were suspended yesterday evening.
Divisional organiser with SIPTU Adrian Kane said the talks had ended without any substantial progress.
They are due to resume again on Friday.
The mine will be placed under "care and maintenance" on 14 July, leading to the temporary lay off of 650 workers.
Boliden Tara Mines has said the decision was taken due to substantial and unsustainable losses at the company.
It cited a decline in the price of zinc, high energy costs and general inflation as factors behind the decision, which it said was taken to safeguard the long term future of the mine.
Adrian Kane said that the "only possibility for the continued operation being secured is if there is a major intervention by the Government".
He will propose a motion at the Irish Congress of Trade Unions conference today.
This motion will call on Government to "urgently engage" with Boliden and the trade unions to "put in place the necessary supports to ensure that the mine remains in production and the workers continue to be paid in full".
SIPTU sector organiser John Regan said that they were reaching the "very last chance for an intervention by the Government in this situation".
"If a positive way forward is not found the temporary closure will have a devastating impact on the workers, their families and the local economy," he said.
