The Taoiseach has strongly defended the Government's decision to allow parole to a number of high-profile republican prisoners in order to attend the Sinn Fein Ardfheis at the weekend.
In a clear reference to the UKUP leader, Mr Bob McCartney - who was scathing about the releases - Mr Ahern said yesterday that those who criticised what happened "seem to have nothing to say other than No".
However, within hours of defending himself, he came under attack from the Fine Gael leader, Mr John Bruton, who claimed he lacked sensitivity and balance.
Mr Bruton said the Taoiseach's remarks that the criticisms had emerged from people who were saying "No" for 30 years were not designed to win maximum support for a Yes vote on a cross-community basis in Northern Ireland to the Belfast Agreement.
"The Taoiseach fails to understand the pain felt by the families of victims of paramilitary crime. Early releases of prisoners are necessary and justifiable but crass triumphalist scenes are inappropriate and so also is the sloganising response of the Taoiseach to perfectly understand feelings," Mr Bruton said.
The Democratic Left leader, Mr Proinsias De Rossa, said that, while the early release of prisoners was an indispensable part of the agreement, "triumphalist parades through ranks of cheering Sinn Fein members of those convicted of appalling crimes is not conducive to a spirit of reconciliation".
"Sensitivity is required and some indication of remorse on the part of the organisation and the individuals responsible for these crimes would help ease the inevitable pain that the relatives of their victims must feel at the early release of prisoners," he added.
Meanwhile, the Taoiseach said he hoped voters who were undecided about the Belfast Agreement would have seen an organisation which was close to violence make an historic decision to turn away from that strategy.
Addressing a Fianna Fail campaign rally on the Belfast Agreement in Cork last night, Mr Ahern also said that consent was at the core of the agreement, not only in relation to constitutional change "but in the operation of democratic institutions both in the North and North-South".
"We now have two-way or parallel consent, which also translates into a mutual veto. That will necessitate close co-operation, so that balanced accommodation that meets the needs of both communities can be achieved on a regular and ongoing basis," he added.
The agreement would require the establishment and strengthening of a working relationship between both the Irish Government and Northern nationalists and the unionist community.
"A better understanding between the Ulster Unionist Party and the Irish Government helped bring about the agreement. We hope in future to be discussing practical matters of mutual benefit to all the people on the island or, in certain cases, people on either side of the Border, and to move away from the exclusive concentration on differences in constitutional aims," Mr Ahern said.
Also speaking in Cork, at a public meeting on the forthcoming Belfast Agreement referendum, the Minister of State for Foreign Affairs, Ms Liz O'Donnell, said Sinn Fein's decision suggested that the republican mindset which saw violence as legitimate had now changed for good.
The ardfheis decision to allow participation in the Northern assembly would, she hoped, prove "a turning point for the republican movement" and a disavowal of violence as a means of achieving its political aspirations.
It was reasonable for democratic politicians, North and South, to require the decommissioning "of not only weapons but of the mindset of those who have espoused violence in the past".
According to Mr De Rossa, the Sinn Fein leadership was entitled to credit for the political courage and tactical skill in not alone having the motions passed, but in securing such a decisive majority for them.