The renewed onslaught by the Minister for Justice, Mr McDowell, against Sinn Féin is motivated by "personal ambition and narrow sectional interest", the party has alleged.
On Monday Mr McDowell said Sinn Féin was under "the control" of the IRA, which posed "a clear and unambiguous threat" to democracy.
The latest challenge by the Progressive Democrats politician was rejected by the Sinn Féin president, Mr Gerry Adams, even though it dominated his party's election launch in Dublin.
"I would say it is obvious that there is going to be a leadership battle within the PDs. This is Michael putting personal ambition and narrow sectional interest before the Good Friday agreement, which has been the most remarkable achievement," Mr Adams said.
Repeating remarks carried in his latest book, Hope and History, Mr Adams said the Taoiseach, Mr Ahern, had left him in no doubt during the Good Friday negotiations that the killers of Det Garda Jerry McCabe would be released under its terms.
Rejecting denials issued to date by the Government, Mr Adams declared firmly: "They were not in the room. I have told you what happened." The Sinn Féin leadership could not have persuaded the IRA and its own supporters at the time unless they had been sufficiently "assured that everybody was going to be released".
Mr McDowell had been a long-time enemy of the peace process, said Mr Adams, during his time as a "pin-up" columnist in the Sunday Independent. Mr McDowell had to be "fairly muted" in the period immediately after the signing of the agreement, although he had been able to be more vocal again as "the last couple of years have become more difficult. Obviously, there is some point to this. It isn't just a rant. All of that is fair and legitimate. Where I take issue with him is where he places the peace process into second place," the Sinn Féin leader said.
Sinn Féin is clearly worried that the renewed McCabe controversy will deter "soft" support that could fall its way on June 11th in the local and European Parliament elections.
Questioned about the Minister's speech in Limerick, Mr Adams at one point said: "I don't want to talk about the PDs. They can get their own publicity."
He rejected Mr McDowell's assertions that Sinn Féin was partly funded by the IRA's criminal activities. "That is not true. The party is wholly independent. The core authority of the party is the ardfheis. That meets annually. There is a free vote where their conference is a bandwagon for a speech," he said.
Rejecting the Minister's allegations that the IRA was nothing more than a criminal enterprise, Mr Adams said: "I have no doubt that like any other political association some republicans might have fallen."
However, he said the vast majority of republicans believed in what they were doing, citing the example of those who went on hunger-strike in the H-Blocks and Armagh jail in the early 1980s.
"Republicans get quite upset about all of this. Margaret Thatcher was the one who branded the IRA as a criminal enterprise," he said.
Questioned about Mr Adams's claims yesterday, the Minister for Justice said the Taoiseach had repeatedly said that the McCabe killers were not included.
Mr McDowell said he was faced with the choice of believing the Taoiseach, who had been consistent throughout, or Mr Adams, "who is a man who denies that he was a member of the IRA".
