A rocked Labour has rounded on its rebel chairman, with senior party members calling for his resignation.
Chief whip Emmet Stagg joined Tanaiste and Labour leader Eamon Gilmore in saying defector Colm Keaveney's position was untenable.
Mr Keaveney dealt the party a damaging blow when he became the fifth TD to revolt in the 20 months of the coalition after refusing to back savage social welfare cuts.
Mr Stagg said: "He comes out against the Government and against the Labour Party in Government.
"I don't think it's a tenable position, I think he should quit the position forthwith."
Mr Keaveney joins rebels Roisin Shortall, Willie Penrose, Tommy Broughan and Patrick Nulty on the party sidelines.
However, he vowed to fight tooth and nail to maintain his chairmanship of the party - a position he was appointed to by Labour members and that he can hold regardless of his exit from the parliamentary party.
Earlier, Mr Gilmore said it was not appropriate for someone who was not in the parliamentary party to hold senior office, while Communications Minister Pat Rabbitte claimed now was not a time for political narcissism.
He accused Mr Keaveney of being self-indulgent and failing to stick to the tough decisions made by Government in the best interests of the people. He too called for the chairman's resignation.
Mr Keaveney was the only Government TD to vote against the social welfare Bill on Thursday.