Mattie McGrath says his group is 'pleading with the Government' to listen to those opposing the St James's site
Parents of sick children will attend a Dáil debate today over the new National Children's Hospital.
Planning permission was granted last April for the new hospital at the St James’s Hospital campus in Dublin city.
The new hospital will have more than 470 beds for patients, as well as a 53-bed space for family accommodation.
Opponents to the central Dublin location have said the new hospital would be better located on a campus off the M50 motorway - with campaigners suggesting the campus of Connolly Hospital in Blanchardstown as a more appropriate site.
Others have highlighted worries about the cost of the project, with recent figures suggesting it could cost in excess of €1bn - despite initial estimates of around €400m.
A Dáil motion by the Rural Independent Group asks why the current plan is going ahead despite concerns over access and spiralling costs.
The motion calls on the Government to note "that accessibility to the proposed St James’s Hospital site for patients, staff and medical personnel will lead to extreme levels of congestion and increase the risks of adverse medical outcomes".
It also calls for evidence to support claims "of improved clinical outcomes resulting from adult hospital co-location".
Jonathan Irwin - the founder and chairman of the Jack and Jill Foundation - will be among those gathering at Leinster House later today.
He argues: "Connolly is better option all round and unlike St James’s they have the room and the reality of a maternity hospital with the Rotunda being relocated there.
"The solution of flipping the sites making Connolly the core children’s hospital and St James’s one of the satellites makes much more sense, and we hope that common sense prevails."
Mattie McGrath, a member of the Rural Independent Group, said: "It cannot be pushed ahead simply to accommodate the inability of government to politically acknowledge that it has made a catastrophic mistake that will impact generations of sick children."
"Even at this late stage, we as a Group are pleading with the Government and indeed all members to reflect on the evidence and listen to the thousands of families who oppose this site."
A number of experts have, however, defended the St James's site.
In a letter about the decision, eight prominent clinicians write: "We are working towards the delivery of healthcare services on this single academic medical campus which will provide paediatric, adult and maternity services.
"The delivery of these services side by side, on a research-intensive campus, will benefit all of our patients, but in particular will drive improved clinical outcomes for the sickest children, adolescents, new-borns and high risk mothers.
"This ’tri-location’ model of healthcare delivery is recognised as best practice internationally and, as clinicians, we are greatly excited about the bringing together of our services on one campus," they add.