Fianna Fáil is considering tabling a motion of no confidence in the management of An Garda Síochána next week.
The Irish Times understands the hardening of position follows a meeting of the party's front bench where senior Fianna Fáil TDs strongly criticised Garda Commissioner Nóirín O'Sullivan.
The party’s justice spokesman, Jim O’Callaghan, told colleagues he would have removed the commissioner from her position if he was in government.
Mr O'Callaghan was supported by senior TDs Timmy Dooley, Michael McGrath, Billy Kelleher, Dara Calleary and Darragh O'Brien.
The meeting heard the party cannot express confidence in the commissioner, and strongly criticised her failure to answer a series of questions at an Oireachtas committee meeting last week.
Despite previously saying that it would not support a motion of no confidence in Ms O'Sullivan in the Dáil, and that involving parliament would politicise the Garda, Fianna Fáil is now preparing its own motion which will express no confidence in the management of An Garda Síochána. This is similar to wording by the Labour Party, which has tabled its own motion.
One Fianna Fáil TD said he fully expected Ms O'Sullivan's own position to be 'front and centre' when Garda motions come before the Dáil next week
The motion, which has yet to be drafted, will not be personal towards the commissioner, but will condemn the management of the force for the controversies which have emerged in recent weeks regarding the exaggeration of breathalyser tests and the wrongful conviction of 14,700 people for motoring offences.
It will also fully outline its belief that public confidence in the force and in the management has been undermined significantly.
One Fianna Fáil TD said he fully expected Ms O'Sullivan's own position to be "front and centre" when Garda motions come before the Dáil next week, and that the party's initial proposals on giving extra powers to the Policing Authority would be substantially strengthened.
Ms O’Sullivan is also facing further questioning from the Oireachtas Committee on Justice following her appearance last week. The committee has agreed to send 15 questions to Ms O’Sullivan for further replies, including asking her to outline her knowledge of any further discrepancies in Garda figures.
She will be asked to submit the responses in writing within a week or could be called to given evidence again.
Meanwhile, Tánaiste Frances Fitzgerald has secured Cabinet approval to establish an independent root and branch review of the Garda.
Ms Fitzgerald’s report will focus on four different areas, including the training and recruitment of gardaí, oversight and accountability, culture and ethos and the structure of the force.
The Tánaiste is to request the opinions of Opposition parties and other interested bodies, including the Policing Authority, the Garda Síochána Ombudsman Commission and the Garda Commissioner.
The Government will appoint a chairperson to the review panel, who will be assisted by a number of international experts.
Fianna Fáil is to seek a specific measure to examine the management of gardaí, and whether gardaí should be allowed to facilitate promotions from within.
For us the management and supervision of the force is the main issue
Mr O'Callaghan told The Irish Times this could stretch to appointments in districts and regions, and also the hierarchy of the force.
“For us the management and supervision of the force is the main issue, and whether more civilians should be appointed to management positions. How many of the management team in An Garda Síochána have management experience?”
Mr O’Callaghan added that the review team must also engage in public meetings across the country to assess views on the reforms that are required.
Fianna Fáil and the Independent Alliance are to seek the appointment of former Northern Ireland police ombudsman Nuala O’Loan to the position of chairperson.