But James Reilly says he does not believe the government "got it so wrong"
A former health minister says the new National Children's Hospital is now unstoppable.
James Reilly held the health portfolio when the site at St James's Hospital in Dublin was selected.
Some 80% of the country's county councils have so far passed a motion against the planned location, according to the Connolly for Kids Hospital group.
Back in 2012, Mr Reilly said the site offered scope for the building not only of a children's hospital, but also of a new maternity hospital in the future.
While speaking to Newstalk Breakfast today, he said: "I think any people now who have the best interests of children at heart will be supportive of this project and want to see it built".
"We've been at this for a quarter of a century, one way or another, let's give our children the best of medical treatment which they can get now - but in the best possible environment which we can build for them".
"Let that be part of Ireland's modern society and a display of its attitude to our children, who were not always looked after in the way that they should have in the past", he added.
On his record in health, Mr Reilly said: "I don't believe we got it so wrong".
He defended the changes he implemented on trolleys, inpatient waiting times and quantifying outpatient waiting lists.
"But we ran foul because of a budget - 2013/14 - it simply wasn't, from my point of view, workable when it came to the medical card scheme and sadly it proved to be so".
He added that he regrets distress caused by the medical card changes: "I was very glad that that was reversed before I left, but I nonetheless still regret that it happened in the first place".