A former head of the HSE says the Sláintecare reform plan needs to be moved away from the Department of Health.
Tony O'Brien was speaking following the resignation of two senior officials from the group.
Laura Magahy and Tom Keane stood down from their roles on Wednesday, saying that requirements for the plan were seriously lacking.
Eleven members of the Sláintecare Implementation Advisory Council say they are concerned at the "shock" resignations.
Sláintecare commits to end private practice in public hospitals, and provide universal healthcare as well as free GP care.
The council says it is actively seeking answers from the Department of Health about the events that led to the two senior members standing down.
Mr O'Brien told The Hard Shoulder the plan should be 'elevated' from the department.
"I think there are questions about the appetite for change within certain parts of our system.
"Obviously the HSE will have a reduced appetite for change as it's coming out of 18 months of hell, effectively, for the health service.
"The problem is that you need to see momentum for changes in the future - notwithstanding the present challenges - and it would appear from these resignations that they don't see that potencial right now.
"And that could be because one of the key recommendations that this all-party Sláintecare committee came up with about where this thing should sit, where it should be controlled from, was disregarded under the previous government [and] that's continued under this one.
"But because this is a new Government, with these dramatic - some might say unprecedented - resignations, it does create an opportunity for that to be reviewed.
"So should this sit within the Department of Health, or should it sit at a higher level within Government - reflecting the significant priority?"
And he says keeping it in the Department of Health could lead to more issues.
"This doesn't have the authority or the direct oversight of the Department of the Taoiseach, it's located in the Department of Health.
"And one of the challenges about that is there is historically ambiguity about the relative roles of the Department of Health and the HSE.
"There are often tensions about those roles, and for something as big and important as Sláintecare, it really does need to be elevated above that".
But he says the time for debate around the plan itself is over.
"The problem with any plan is that everybody can say 'Yes', but we should do this instead, or maybe we should do that instead.
"Everyone has an opinion, and that's great, the problem is at some point the rubber's got to hit the road.
"This is currently the plan - unless someone comes up with a different plan and starts implementing that, the challenge right now is to implement the plan we have".