Sinn Fein looks set to lose one of its most promising politicians after he slammed Gerry Adams' comments about two RUC officers murdered by the IRA being lax about their security.
Peadar Toibin rejected outright Mr Adams's claim that Chief Superintendent Harry Breen and Superintendent Bob Buchanan displayed a "laissez faire" approach to their safety prior to their murder in 1989.
Now the Meath West TD has told his supporters that he is likely to quit the party in the new year.
In a clear indication of his dissatisfaction with the Sinn Fein leader, Mr Toibin last night directly contradicted Mr Adams's comments about the deaths after the Smithwich Inquiry report into collusion in the Republic.
"I don't believe it's ever correct to say that two police officers were murdered because of their own actions," he said.
"These men's deaths were not determined by their own actions but the actions of the IRA. The IRA is responsible for the murder of these two men, not the officers themselves."
Mr Toibin's rebuke came as sources in Meath West confirmed that he was preparing to leave the party. While he did not want to comment on the matter last night, well-placed sources said he had already held talks with members of other parties.
The news of Mr Toibin's expected defection will prove to be a major blow for Mr Adams, who is due to travel to South Africa to attend memorial events for Nelson Mandela.
While Mr Adams has received the backing of some TDs, others, such as deputy leader Mary Lou McDonald and finance spokesman Pearse Doherty, did not respond to a request for comment last night.
Dublin North West TD Dessie Ellis refused to support the use of the phrase "laissez faire" by Mr Adams, but said the two officers had been "lax" in relation to their security.
"I know the area and you don't get away with that, even the Brits themselves wouldn't travel like that," he said.
Padraig McLoughlin, Caoimhghin O Caolain, Brian Stanley, Jonathan O'Brien, Martin Ferris and Sean Crowe all said they supported their leader.
Mr Toibin, one of the Dail's youngest TDs, was suspended by Sinn Fein in July after voting against contentious abortion measures. Sinn Fein believed he would return in the new year.
But it has emerged that Mr Toibin has engaged in serious discussions with senior Fianna Fail figures about a potential move to Micheal Martin's party.
Sources in Meath West have said Mr Toibin is likely to vote against Sinn Fein again over two private members' bills on the issue of abortion. A source said: "Peadar is prepared to vote in line with his conscience. That will mean he will defy the party again."