The Ulster Unionist Party's main anti-agreement figure, Mr Jeffrey Donaldson has rejected Mr Blair's description of today's difficulties as a "glitch".
Speaking on Channel 4 News tonight, Mr Donaldson said: "It's much more than a glitch. This is a major embarrassment for David Trimble.
"He thought he had concluded a deal with Gerry Adams and the IRA didn't deliver. That's absolutely clear. I think the IRA have hung David Trimble out to dry tonight.
It's difficult to see how they are going to put this back together again.
"It's not just a question of the transparency of what the IRA may have done on decommissioning. Even the statements made earlier in the day by the IRA fall well short of what unionists required."
Mr Donaldson said the IRA had failed to answer the three questions posed by Tony Blair in May: is their war over? is decommissioning going to be completed? and is all paramilitary activity going to end?
"The process has undoubtedly faltered today and the words and actions that unionists needed to hear and see from the IRA have not been delivered," he said.
Mr Donaldson said elections should go ahead despite today's setbacks.