Kildare North TD, Catherine Murphy, is party co-leader.
The Foreign Affairs Minister's facing mounting calls from the opposition to resign ahead of a no confidence motion in the Dail tomorrow.
The motion centres around Simon Coveney's handling of the appointment of Katherine Zappone to a UN Special Envoy role.
He has faced criticism for offering the newly created job to a former minister without it being publicly advertised.
Government ministers have described the vote as a "publicity stunt" but Labour has indicated it'll be supporting the Sinn Fein motion.
Social Democrats co-leader, Kildare North TD Catherine Murphy, says they'll also be backing it:
Deputy Murphy says the minister's attempts to put the issue to bed at recent committee meetings failed