Irish Justice Minister Charlie Flanagan is facing a major backlash after doing a deal on vetting future judges with Sinn Fein.
As significant changes to the way judges in the Republic are selected neared completion, Sinn Fein's chief whip Aengus O Snodaigh claimed judges in the Special Criminal Court have shown "anti-republican bias".
The non-jury Special Criminal Court in Dublin deals with terrorism and serious organised crime cases.
But Fine Gael is determined to press ahead with a behind-closed-doors deal with Sinn Fein to ensure the Judicial Appointments Bill, championed by Minister for Transport Shane Ross, is passed.
Fianna Fail's Thomas Byrne last night described the arrangement as an "unholy alliance" and he said Sinn Fein's motivation in supporting the bill may be to "get revenge on the courts system".
There is deep unease within Fine Gael over its newfound relationship with Mary Lou McDonald's party, leading Taoiseach Leo Varadkar to tell a private party meeting last night that there is "no deal".
But Ms McDonald's party has backed the legislation in return for assurance from the Justice Minister that he will introduce sentencing guidelines.
She said it is important for her party "to get a result" in this area "because we have been very conscious that serious crimes against the person, particularly sexual crimes, were carrying sentences that frankly were raising big concerns and questions in the public mind".
Mr Ross has made the ending of political power over the appointment of judges a red line issue for his participation in Leo Varadkar's minority government.
A key component of the law is that the advisory committee who will recommend judicial nominees to Cabinet is to have a lay person majority.
During a debate on the issue Mr O Snodaigh said judges in the Special Criminal Court had shown "anti-republican" bias and while, he said, the proposed advisory committee would not necessarily address the issue, he welcomed the idea of a lay majority as "they come with a different view of the world".
Mr Flanagan has denied there was any deal struck with Sinn Fein and said the government must work with people from all parties and none to promote its legislative agenda.
Despite government insistence that no deal was struck, Sinn Fein's justice spokesman Donnchadh O Laoghaire said the party "sought and secured this commitment on sentencing guidelines".
Finance Minister Paschal Donohoe said he would "prefer" if the government didn't have to rely on Sinn Fein, when asked if he was comfortable with the arrangement.
Mr Donohoe said: "Fine Gael will not be going into government with Sinn Fein. Sinn Fein vote against Fine Gael and our party, far more often than they vote for us."
Meanwhile, Ms McDonald yesterday attempted to distance herself from her chief whip and defend him at the same time.
Asked directly whether she agrees with Mr O Snodaigh, she replied: "The Special Criminal Court has a history of itself.
"I am not interested in rewriting and revisiting the history books on this matter.
"We have every interest in due process and the sound and fair administration of law and for us at this moment a really critical issue has arisen around sentencing guidelines."