Fianna Fáil leader Micheál Martin's intervention on abortion is the most significant since the start of the debate so far.
In a meticulously crafted speech to the Dáil, he outlined his reasons for supporting a repeal of the Eighth Amendment. He described in detail how he has broadly come to support the recommendations of the Oireachtas Committee and access to abortion through "a time-based cut-off near the end of the first trimester".
He says unless the Eighth Amendment is removed, there is no way to help women with a diagnosis of fatal foetal abnormality who are "forced" to carry to full term.
Just last October, at its Ard Fheis, the Fianna Fáil party voted overwhelmingly to retain the status quo, limiting women from obtaining an abortion within the State.
Until now, Mr Martin's opinion has been rigidly in line with this position. But as a lawmaker of considerable influence and experience, he said he has a "duty" to "question" his own views, and "to be open to different perspectives and to respond to new information".
Mr Martin's thought process needed to be logical and watertight, because no doubt his volte-face will shock some of his colleagues and constituents.
Importantly, he came to his conclusion after he sought to listen to the diverse contributions of women, read the committee's report, the transcripts of its hearings and written submissions.
He recalled how evidence from obstetric experts had a "deep impact" on him. Doctors described how the law gave rise to "significant difficulties for doctors practicing in Ireland and has caused grave harm to women", including death.
Mr Martin said he realised the Eighth Amendment "does not mean Ireland is a country without abortion" and "retaining the Eighth Amendment will not make Ireland a country without abortion".
Moments after he took his seat, a tweet from Patrick Coveney, brother of Tánaiste Simon Coveney, commended him for his "big, brave, personal statement".
That Twitter comment is remarkable for many reasons. Chief among them is that it points again to the absence of Simon Coveney from the discussion. But it also illustrates the divisive and difficult nature of abortion. Health Minister Simon Harris and Fianna Fáil leader Mr Martin have filled the void of leadership from the two most senior politicians in the State.
But if the Taoiseach decides he will vote for the reform as put forward by the committee, it also means that all party leaders are in favour of repeal.