The Ulster Unionist leader has said it is "crunch time" for the Provisional IRA on its commitment to exclusively peaceful and democratic means.
Mr David Trimble said the British Prime Minister's questions to the IRA had to be answered and clarity was extremely important. At a press conference in Belfast yesterday, he warned time was running out.
"It is now crunch time for republicans. This time they have got to bite the bullet. Just as there is no such thing as a free lunch, there is no such things as free political influence and the bill is now sitting on the republicans' table."
Mr Trimble insisted the Assembly elections scheduled for next month must take place in a positive climate. The electorate needed to know if the political arrangements for which they would be voting could work.
His party had no desire to operate a political structure which would be incapable of functioning properly without clarity from the IRA. "Just in case anybody thinks that somehow we can be sucked into as Assembly, just in case republicans are tempted to hold back a positive response in the hope of that, let me make it absolutely clear.
"Without a clear and positive response to the questions the Prime Minister has put, then an Assembly elected on May 29th will not work and we will not ourselves take any steps in that to make it work. We are not going back into an administration unless republicans have made it absolutely clear that the transition is coming to an end."
The fact that Mr Blair had to pose three questions was "an eloquent commentary" on the clarity and certainty of the recent IRA statement, Mr Trimble said.
Anti-agreement UUP MP Mr Jeffrey Donaldson said most people in the North wanted "actions, not words" from the IRA. "The Prime Minister and the IRA can come up with whatever form of words they want but the judgment will be made on the streets of Northern Ireland."
Mr Donaldson warned against postponing next month's elections. "It would be incredible if the Prime Minister allowed the IRA to dictate that the people of Northern Ireland should not have an election. If the government were to postpone elections, it would be for one reason only - the IRA holds a veto over political progress.
The DUP deputy leader, Mr Peter Robinson, said Mr Blair's assessment showed he was prepared to take a statement from the IRA at face value. "It seems to indicate that if the IRA said something, he would believe it. The IRA have proved themselves to have lied consistently throughout the process," he said.
Mr David Ervine, the leader of the Progressive Unionist Party, said it was clear from Mr Blair that the IRA would have to answer the question of whether its war was over.