Fianna Fáil spokesperson on health Billy Kelleher has said the Universal Health Insurance is not the panacea to resolve the problems in the health service.
He said the scheme will not address the problem of people gaining access to health care based on their medical needs.
Speaking on RTÉ's News at One, Mr Kelleher claimed the scheme would allow private health insurers to decide the basic suite of cover that will be available to families.
Mr Kelleher said there would be a section of middle Ireland that would be "absolutely crucified" with the requirement to take out health insurance.
He said the key issue was having to define who can and cannot afford to pay for Universal Health Insurance.
Mr Kelleher also criticised Minister for Health James Reilly saying he still did not know the rough cost of Universal Health Insurance after three years in his position.
He said the Government's plan for the scheme will mean increased spending on health, which would have to come about either by increasing the cost of premiums that people will be obliged to buy, or by increasing taxes to subsidise it.
Meanwhile, the Cabinet sub-committee on Health will be given a draft of the White Paper on UHI for the first time later today.
There have been several versions of the document with discussions between the Department of Health and other departments.
It may be some weeks before it goes to Cabinet and the final version is published.
There will then be public consultation on what the standard basket of services to be provided under the system should be.
The preliminary paper on the move to UHI, published last year by the Department of Health, said it would be mandatory for people to have health insurance.
In recent weeks, the Department of Public Expenditure and Reform has raised questions about the cost of UHI to the State, while the Department of Finance has insisted there needs to be a cap on State spending on health with UHI.
The latest version of the White Paper will provide for such a cap so that it does not exceed a certain level of national income.
The exact cost of UHI from 2019 is not yet known.
The Department of Health believes that the cost of drugs and treatments should both have reduced by that point.
UHI is promised by 2019 under which the State will fund in full, or in part premiums for people who cannot afford them.
As everyone will be required to have UHI, those who refused to take out cover could have the cost deducted from their income.
UHI is to be funded through taxes, insurance premiums and co-payments, but the exact mix of how this will work remains unclear.
Co-payments may apply for some drug costs.