The Taoiseach has said Gerry Adams's call for the IRA to end its "armed struggle" and fully embrace politics can only be judged on the basis of what the IRA does next.
Mr Ahern's conditional welcome yesterday for the Adams statement came as Opposition leaders expressed scepticism over its timing and sincerity.
Mr Ahern said that Mr Adams' statement was "significant and has potential". But he added: "Ultimately this statement can only be judged on the basis of the IRA's actions on foot of it."
Suggesting that Mr Adams' statement could be related to the upcoming Westminster elections he said: "We are mindful that the elections are now underway and naturally approach any comments made in that environment with some caution."
He said that nothing less than "a complete and decisive end to all IRA activity and capability" was acceptable if there was to be any prospect of achieving inclusive politics in Northern Ireland.
Mr Ahern said it was vital that the IRA's consultations be concluded in a timely manner "and that everyone will know that the necessary steps have been taken, that they will be adhered to and that the IRA is thus moving on".
"For so many years we have had false dawns and dashed hopes," he added. "The last few months in particular have crystallised the challenges that must be addressed. The crisis of trust and confidence is profound and will not easily be repaired. Only a complete transformation of the situation will generate the energy needed to move beyond the current stalemate and realise the full potential of the Good Friday agreement."
Fine Gael leader Enda Kenny said the efforts by Sinn Féin to bill this speech as "the most significant made by Gerry Adams for many years" was an insult to people's intelligence. It came at a time when the IRA was "mired in a web of criminality, from the Northern Bank raid to the brutal murder of Robert McCartney".
"Rather than more so-called 'significant' speeches, I want to see real action from the republican movement . . . Only action to end their involvement with weapons, paramilitarism and crime will convince the Irish people that they are serious about democratic politics."
Labour Party leader Pat Rabbitte said it was a bizarre situation that a man who has been publicly identified as a member of the IRA's army council is "appealing to IRA members, presumably including himself, to take a particular course of action".
He said Mr Adams's appeal to the IRA to "fully embrace fully political and democratic means" was to be welcomed to the extent that it was intended to be construed as an attempt to move the peace process forward. However, it also involved "a very belated recognition of the IRA's refusal so far to embrace either politics or democracy".