Former US senator Mr George Mitchell, who chaired the Good Friday Agreement peace talks, called for UUP leader Mr David Trimble to be given due credit as he bids to be restored to office as Northern Ireland First Minister.
He said: "I would hope that all of those who have been in the unionist side who have been critical of David Trimble's leadership will now recognise that he has been right all along."
Mr Trimble yesterday won the backing of his party's ruling council for a return to government with Sinn Féin following the IRA's historic decommissioning move.
The 110-strong body passed a motion calling on all 28 Ulster Unionist MLAs to vote for Mr Trimble's re-instatement as head of the power-sharing cabinet.
With Mr Trimble needing more than 50 per cent support from both unionists and nationalists in the chamber, complete support from his own benches is crucial in the knife-edge poll expected on Friday.
And praising the risks taken by Mr Trimble to secure peace, Mr Mitchell told BBC's Breakfast with Frost"He has been quite courageous in taking these steps, as have the other political leaders who are part of the pro-Agreement effort."
Mr Mitchell added that he believed all paramilitary organisations will have to put their guns beyond use.
"There is of course now no theoretical or other argument in the way of going forward," he said.
PA