The Social Democrats says it will support a no confidence motion in the Tánaiste Leo Varadkar in the Dáil next week.
On Friday, Sinn Féin announced their intention to table the motion over Mr Varadkar's leaking of an Irish Medical Orgainsation (IMO) contract to a rival union, the National Association of General Practicioners (NAGP).
Mr Varadkar fielded two hours of questioning in the Dáil on Tuesday, apologising for his actions saying it was an "error of judgement".
Social Democrats co-leader Catherine Murphy says they have the "greatest of concern" in relation to the leak.
"The reality of it is that there was the leaking of a confidential document with confidential written on every single solitary page. That is not the standard to be set by a government."
The Labour Party have also said they will support the Sinn Féin motion which will be debated in the Dáil on Tuesday.
Mr Varakdar has described the move as political mudslinging and with the Government majority, it is unlikely that the motion will pass.
On Friday, a spokesperson for Mr Varadkar said the motion shows Sinn Féin are not interested in the truth, only attacking the government at a time of national crisis.
Both Fianna Fáil and the Green Party have voiced their support of the Tánaiste, despite Taoiseach Micheál Martin facing considerable criticism from within his own party regarding his treatment of the matter.
