Fianna Fáil's, Billy Kelleher has said that he is "deeply worried" about patient safety at Tallaght Hospital following a letter he got from an Emergency Medicine consultant at the hospital.
The party's Health spokesperson said the letter sets out the crisis "engulfing the hospital on a near daily basis".
He said: "Last night alone, there were 29 people on trolleys awaiting admission with two people waiting longer than two days.
"Overcrowding in EDs is also causing knock on effects for the ambulance service.
"When senior Emergency Medicine specialists are concerned about patient safety to the extent that they must contact political parties, it’s a damning indictment of Minister Harris' failure as Health Minister to deal with the dangerous levels of overcrowding."
He stressed that hospital staff had outlined what needs to be done to solve the crisis.
He said: "If you ask any Emergency Medicine specialist they will tell you that the way to fix the overcrowding in our EDs is twofold: increase bed capacity in our acute hospitals and utilise our community hospital network to provide step down facilities for patients who while still requiring care do not need to be in an acute hospital setting.
"The number of acute hospital beds has been reduced since 2012 while our population, and in particular the number of older people, has grown."
It comes as the Irish Nurses and Midwives Organisation revealed that the number of people waiting to be admitted to hospitals in Ireland stands at more than 400 today.
At the moment there are 279 people waiting on trolleys and another 138 in overflow wards, according to the latest report from the INMO.
Of the 417 people waiting to be admitted, University Hospital Limerick is the most overcrowded with 43 patients in line for beds.
University Hospital Galway has 40 people waiting to be admitted, while South Tipperary General Hospital is next with 34.