The Garda Commissioner says she 'refutes in the strongest terms' that she engaged in a smear campaign against a whistleblower.
Nóirín O'Sullivan denies accusing Sergeant Maurice McCabe of sex crimes, after he alleged mismanagement in the force.
The claims were made in the Dáil yesterday by Labour leader Brendan Howlin, who said Ms O'Sullivan's position is now untenable.
The Dáil will cover the matter again today when they discuss a new commission of investigation.
TDs Mick Wallace and Clare Daly are expected to suggest two amendments to its terms of reference.