The remaining members of the Sláintecare Implementation Advisory Council say the plan is at a crossroads, and needs political leadership 'more than anything'.
A number of resignations from within the group has prompted the establishment of a new oversight group, which will be headed up by the head of the Department of Health Robert Watt and HSE CEO Paul Reid.
The members of the soon to be defunct council have written to the Taoiseach Michael Martin welcoming plans to tackle three key areas: regionalisation, E-Health and waiting lists.
"We have tried to synopsize our collective view about the current situation, the difficulties the Sláintecare project - the fact that it's four years old - the difficulties of recent weeks.
"And we've tried to put out to the Taoiseach, I think in an analytical and reflective way, what we believe are the remaining challenges and the risks and so on that need to be addressed."
Mr Doran says he hopes this gives the Taoiseach and others "food for thought".
But he says issues around waiting lists, regionalisation and e-health are just part of the problem.
"Those three issues... are very much to the forefront, but what we're tried to say in our final analysis is that yes - those three things must be progressed, they require steadfast resolution.
"But they're not the beginning or the end, if you like, of the Sláintecare project and the Sláintecare policy.
"They are central to it, but there's other issues as well."
He says this includes removal of private practice from public hospitals, questions around community care and manpower planning which "are of equal importance".
Mr Doan says the plan should be implemented as it currently is envisaged.
"I'm born an optimist and... I suppose the reason I was very kindly put on the Sláintecare Implementation Council is that I'm a passionate advocate of a single-tiered system, universal access, need determining access [and] not ability to pay.
"I'll always remain passionate to that... but we're at a crossroads, and we now need political leadership more than anything to deliver for the people of Ireland what was promised.
"I can only hope today's letter and our departing advice to the Government is about trying to say to them 'Look the template is written, the plan is there, no one need reinvent it, no one need reinterpret it'".
And he adds: "If we're to deliver on Sláintecare, we're trying to say to the Taoiseach we can't fixate on one issue because it is a complete panorama of issues.
"And that's why we've said again, and suggested again, that the Taoiseach and his department have got to play a role in the oversight of the policy.
"And we mean that about any Taoiseach, any government and any minister - it's going to span a decade and that means more than one government, possibly three governments".