The INMO is warning it is likely to give the go-ahead for industrial action unless there is a "radical change" in the management approach to staffing.
Talks at the Workplace Relations Commission adjourned without agreement last night, and the group is accusing health service management of having no funded workforce plan to address the issue.
Meanwhile, TDs and Senators will discuss the record level of those on trolleys in recent weeks and the impact this has on patient safety.
Latest figures show there were 520 patients waiting for a bed yesterday.
President of the Irish Association of Emergency Medicine Dr Emily O'Connor will be one of those speaking at today's Oireachtas committee. She said: "What we need is a year-long focus on emergency department crowding and a year-long implementation of resourcing and solutions."
The INMO's executive council will meet on Monday next week to consider the situation, and is pointing out 90% of its members recently voted in favour of taking industrial action over staffing, if necessary.
General Secretary Liam Doran says nurses are struggling to cope, and are under "intolerable pressure".
"They're unable to meet the care needs of the patient. For the patients as well, it means their environment is totally unacceptable - no privacy, no dignity (and) personal hygiene is a problem…It's a totally unacceptable situation," he said.