The Dail will debate a motion on the new National Children's Hospital at the site of St. James, today.
The Rural Independent Group motion is asking why the current plan is going ahead despite concerns over access and spiralling costs.
Also at the debate will be families of some of the children who use the existing facilities.
Jonathan Irwin from the Jack and Jill Children's Foundation is against the south inner city site.
He said: "This has never been about children, its really so shocking. And you know I can't believe that the budget goes from €400 million to €1 billion and no one says, look lads lets just talk about this. "
He added: "It's just amazing me that former Health Minister Leo Varadkar took over from James Reilly, Simon Harris grand fella that he is, took over from Varadkar, not one of them said why don't we review this, this is getting out of control. There was a 60 thousand petition to Enda Kenny and 73% poll against St. James, nobody listens to the parents."
The €1 billion euro project will be the largest undertaken in the history of the state.
Campaign group, Connolly For Kids believes the hospital should be built on a greenfields site at Connolly hospital.
An Bord Pleanala has approved planning permission for the project in Dublin 8.
A group of consultants from Crumlin Children's Hospital, Tallaght Hospital, the Rotunda and Temple Street believe the new National Children's Hospital will be amongst the best in the world.
In a statement they say: "We fully support the new children’s hospital on a campus shared with St James’s Hospital and we are working towards the delivery of healthcare services on this single academic medical campus which will provide paediatric, adult and maternity services."
It added: 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."