Fianna Fáil is insisting that there has been a change in the way the Government apply their discretion regarding the medical card scheme.
The coalition is targeting €113m in savings from "improving the accuracy" of the scheme - but they say they don't know how many people will lose their cards.
Fianna Fail's Health Spokesman Billy Kelleher says the Government is being "disingenuous" in how it has presented the cuts, which he says will affect thousands of seriously ill people.
And Fianna Fáil Senator Thomas Byrne said that the evidence regarding the changed medical card scheme is clear for everyone to see.
"There was a change in the criteria on the financial tests and the means tests for the medical card," Senator Byrne said.
"But there's also been a change in the way they apply their discretion, as regards people who are very very sick, or oftentimes disabled, who are maybe slightly over the income limit - there's a massive change in that."