The Fianna Fáil leader Micheál Martin has accused Simon Harris of not being on top of the Health brief.
Mr Martin said the recent scandals at the new National Children's Hospital and CervicalCheck show Minister Harris is "not up to the job" and said the Government took its eye off the ball when it came to the massive overruns on the project.
Deputy Martin thinks the Government has not managed the Health Department properly before adding that a report published this week into cost overruns showed the Government has mismanaged it.
He said: "I get the sense that Ministers are not on top of their brief and I don't think Minister Harris is. The only defence that they have is that 'nobody told us anything about this'.
"It's fundamentally about mismanagement of a new project, the Government are using a new language now, they know it was a growth underestimation, we got the estimation wrong.
"I think it's very clear if you read the report that noone was on top of this."
The review found weaknesses in the planning, execution and governance of the project which could now exceed €1.7bn.
Deputy Martin said it is hard to understand how red flags were missed.
He said: "It does represent a damning indictment of Government stewardship of the National Children's Hospital, there is no question their eye was taken off the ball.
"The idea that noone took any notice of this for about 18 months beggars belief and is very difficult to comprehend."