The Justice Minister Frances Fitzgerald has said she has no evidence that the Garda Commissioner has done anything wrong.
Minister Fitzgerald also hit out at opposition parties, saying many of the current garda controversies started when Fianna Fáil were in power.
The Tánaiste may face a vote of no confidence brought by opposition parties if she refuses to sack Commissioner Nóirín O'Sullivan.
The Commissioner has faced calls to resign in the wake of a string of controversies from the alleged smearing of whistleblowers, to inflated breathalyser test results and a furore over financial irregularities in the garda training college at Templemore.
However, Frances Fitzgerald has again expressed her confidence in the Garda chief, saying: "I have no objective evidence that the Garda Commissioner has done anything wrong.
"Of course the opposition are going to ramp up the pressure and use the Commissioner to ramp up pressure on me.
"I would say politics and political expediency are not going to root out the very deep-seated issues in relation to An Garda Síochána."
Meanwhile, the Tánaiste said whistleblowers must be treated with respect, in the wake of revelations at the weekend about garda whistleblower Keith Harrison.
It is reported a profile report was prepared on garda Harrison, similar to what would be drawn up for criminals.
Minister Frances Fitzgerald said the Charleton Inquiry will be looking into whistleblowers’ cases, and said major changes were afoot in the Gardaí.
"I want whistleblowers to be treated with respect," she said.
"Yes, there have been quite a number of issues in relation to policing in recent times, but I would say again (that) when you shine a light, you see issues that have been kept in the dark previously."