The Irish and British governments want to restore the Northern Ireland Assembly for a fixed period in a bid to advance the peace process and get the executive running again, according to the Taoiseach.
Bertie Ahern told the Dáil that the Assembly "cannot meet in shadow fashion", since that was opposed by the SDLP and Sinn Féin. If other parties wanted it to meet "in that interim form, we must find a bridge between their viewpoints".
It would be helpful if the Assembly were up and running and could "lead very quickly to form an executive".
However, if the executive had not been formed by a specific date, "we would have to re-examine matters".
He hoped the two governments would never have to consider a "plan B" alternative to the Belfast Agreement but, "if difficult decisions need to be taken, we will do so".
He added: "If we get to a situation where we cannot get a working executive going, then obviously we must look again."
They would "not consult in advance on something totally hypothetical at this stage".
Mr Ahern warned that "a fixed period must be set as there would be no point in trying to set up an ineffective shadow executive that would just go on and on".
During Taoiseach's questions, Mr Ahern said the two governments had made clear that "2006 will be a decisive year".
He did not want to consider an alternative to the Belfast Agreement. "All I want to say about plan B is I hope we never get there," he said.
"It is not something on which I want to speculate or comment, but we could get to that position this year because we will not let this drift."
Green Party leader Trevor Sargent said that the process could not be moved forward by "Government diktat" and "direct rule vetted by a toothless assembly does not meet the terms of the Good Friday agreement".
Mr Ahern said he agreed with Mr Sargent that the two governments did not wish to go outside the Belfast Agreement but wished "to stick to it absolutely".
"If we are forced from that, we intend to stick to it as closely as possible."
Labour Party leader Pat Rabbitte said the eighth anniversary of the Belfast Agreement was approaching and "a great deal of the good will created by it is in danger of dissipating".
He asked what the implications would be for the North-South bodies of the notion of a shadow assembly if there were a commitment to reviving the executive within a short period.
Mr Ahern said the word "shadow" created major difficulties for some parties.
"I do not like the concept either, since it is not a full assembly. I see no need to have it in shadow form."
Sinn Féin's Dáil leader Caoimhghín Ó Caoláin said if the Democratic Unionist Party continued to refuse to share power after the Assembly met, then it would have to be closed.
"A sham assembly with no executive and no all-Ireland structures would be nothing more than an unacceptable failure."
Mr Ahern said he hoped they would never get to a plan B.
