Sinn Fein will table of motion of no confidence in Simon Coveney shortly.
The Dáil returns after its summer recess on Wednesday and this motion is likely to be one of its first pieces of business.
It follows the failed appointment of Katherine Zappone to a UN Special Envoy role.
The opposition party says it wasn't done in a transparent process and amounted to cronyism, while also falling below the standard expected of Government.
The motion, which will be filed this morning says Minister Coveney failed to explain the handling of this appointment in a credible manner.
Sinn Fein had said it wouldn't table the motion if the Foreign Affairs Minister if he was sanctioned by the Taoiseach, however they feel that hasn't happened.
At the Fianna Fáil think-in in Cavan, Taoiseach Micheal Martin expressed confidence in Minister Coveney.
The Foreign Affairs Minister in New York chairing a meeting of the UN Security Council.