Junior minister Lucinda Creighton has given her clearest indication that she cannot support proposed legislation allowing limited abortion.
The Minister for European Affairs has yet to declare exactly how she will vote, but warned she has grave misgivings on the reforms and will vote with her conscience.
"If this Bill is genuinely to live up to its title... then it should simply aspire to do just that - provide protection to all lives. No more, no less," Ms Creighton said.
Four of Ms Creighton's fellow Fine Gael TDs have already confirmed they will not support the legislation - Terence Flanagan, Peter Mathews, Billy Timmins and Brian Walsh. But it is understood as many as 10 could ultimately vote against it.
Like those who have already set out their stall, Ms Creighton said she was deeply concerned about the proposed changes that will give medical professionals the right to terminate a pregnancy if an expectant mother is at risk of suicide.
The Dublin South East TD - the only member of Government in a ministerial position to express such deep reservations - said the suicide clause should be removed completely.
Taoisdeach Enda Kenny later ruled that out saying it would be counter-productive.
"The reality is, whether people agree with it or not, that the constitutional right on these grounds already exists. If this Bill were to ignore this reality, that right would still exist but in a totally unregulated manner," he said.
Ms Creighton also called for a term limit on when a pregnant woman could be allowed to have an abortion. Mr Kenny said it was not necessary as medics will continue to be constitutionally obliged to save both the life of the mother and baby where possible.
A series of votes on the Protection of Life During Pregnancy Bill 2013 are expected to begin in the Dail on Tuesday with the Government committed to passing the reforms into law before the summer recess.