THE health minister has said he is unable to give specific details on the controversial measure to save €113m from the review of medical cards.
But Dr James Reilly added the medical card issue will be subject of a "cross Cabinet review" that will also involve the Department of an Taoiseach.
The measure will involve increasing the scrutiny and probity of medical cards
Up to 35,000 people over the age of 70 are set to lose their full medical cards as a result.
Instead, these people will revert back to a free GP card in a move that will save the Exchequer €25 million.
Speaking at his post Cabinet briefing at Government Buildings, Dr Reilly also defended the move to grant free GP care to under 5s, dismissing suggestions that it was driven by political rather than healthcare motives.
It has emerged that it is likely to take several months before the legislation necessary to give effect to the measure will even come before Cabinet.
Defending the move, Dr Reilly said: "Parents find fees for GPs quite the barrier and children become quite unwell as a result and end up in hospital.
"It is a step toward getting rid of the two tier health system," he added.
"This is going to be the most challenging year the Health service has yet faced," the minister added.
Health Service Executive (HSE) Chief Executive Tony O'Brien said that "unavoidable pressures critical service priorities and programme for Government commitment will make this a very challenging period.
"We are entering the most challenging period in the health service plan delivery,” he said.
Dr Reilly came under sustained questioning throughout the briefing about the proposed saving of €113 million as a result of the medical card cull.
The minister said this would be achieved by increased “scrutiny” of card holders and “probity”.
Dr Reilly admitted it was a "challenging figure", but could not indicate how many medical cards are likely to be affected.
"It is difficult to give an estimate of how many cards are involved," he told reporters.
He described it as the "toughest Budget" this Government has had to make, but claimed it would be the "last of the really tough Budgets".
Dr Reilly also said legislation to abolish the HSE will come in next year.
At the same press conference, HSE chief Tony O'Brien said only €110 million out of €150 million of Haddington Road savings will be achieved this year, leaving a shortfall of €40 million.
In a further indication of the hostile relationship between the HSE and Brendan Howlin's Department of Public Expenditure and Reform, Mr O'Brien said the numbers working in the health service will not be in line with DPER.