Sinn Féin leader Mary Lou McDonald has said Justice Minister Helen McEntee's explanation of how she appointed Seamus Woulfe to the Supreme Court is 'not plausible'.
Minister McEntee faced questions in the Dáil on the issue earlier.
The Government has been accused of cronyism in appointing Mr Justice Woulfe, a former Fine Gael Attorney-General, to the Supreme Court while sitting judges were also interested in the job.
Minister McEntee said she stood over the process - and that there was a discussion between her and the Tánaiste before she presented a name to Cabinet.
She said: "I did have a conversation informally with my colleague and with the Tánaiste.
"He informed me himself that there was a vacancy that Seamus Woulfe had come through that process - I informed him that I was already aware of that.
"He also informed me - or, I suppose, gave a view - that he thought Seamus Woulfe would be a good judge.
"I did not make a decision then, because at that stage I did not have all of the other names".
Ms McDonald told The Hard Shoulder she sees this as 'nod and wink' type politics.
"The explanation that she has offered for her own actions - that she acted alone, looked into her heart - and selected Seamus Woulfe from what we now know is actually six contenders - five sitting judges and Seamus Woulfe the out-going Attorney-General - isn't plausible.
"It's no more plausible now than it was a week ago."
But she said Minister McEntee "certainly clarified one matter" about how she took an opinion from Mr Varadakar.
Ms McDonald added that they have learned nothing else about the process itself.
"Beyond that, we have got no information as to how she made a decision to whittle down a list of six people down to one person".
"But we do know that Leo told her that Seamus would make a good judge and you have to assume, therefore, that that ultimately was the criterion".
Ms McDonald said while Minister McEntee "has agency", she gave no evidence as to how a decision was made.
"We didn't ask about the relative merits or de-merits of any individual candidate, but we did ask 'Look, you had a list, you whittled it down to one - on what basis did you whittle that list down?'
"She could not answer that question, except to say that the leader of Fine Gael - her boss - said to her that Seamus Woulfe would make a good judge, and she took that into account".
"This is what you get when you have Fine Gael in Government, and this is what you get when you have a Fianna Fáil Taoiseach who is happy to tolerate this 'nod and wink, old boys club looking after your friends' type politics".