The British and Irish governments are concerned that a high-risk, high-stakes brinkmanship game being played by the DUP and Sinn Féin over photographic proof of decommissioning could jeopardise the prospects of a deal to restore devolution being formalised next week, according to informed sources.
Most elements of the package designed to restore the Northern Executive and Assembly are now in place and there is a real possibility of a deal early next week, possibly on Tuesday, all sides generally agree.
But despite the growing optimism, the issue of photographic verification of IRA decommissioning which the DUP demands could yet prevent a deal being signed next week, informed insiders have warned.
In such an eventuality the governments would be disposed to publish their blueprint for restoring devolution to allow the public to assess whether it was a fair deal, and to allow people determine which party - the DUP or Sinn Féin - was chiefly responsible for the collapse of the deal, The Irish Times was informed.
"The way the package is looking at the moment that could be quite an own goal by the DUP," said one informed talks figure.
A number of sources made it clear that the Taoiseach, Mr Ahern, and British Prime Minister, Mr Tony Blair, believe Dr Paisley when he said that, without visual evidence of IRA disarmament, he would not endorse the deal.
This was why the requirement for visual proof of decommissioning, to be produced after the DUP demonstrated it was sharing power with Sinn Féin, was included in the governments' paper for restoring devolution.
But Dr Paisley has insisted to Mr Blair, whom he met at Downing Street yesterday, that the DUP is not prepared to accept future visual proof of decommissioning from the IRA, if it were available, but wants photographic proof of decommissioning before he would share power with Sinn Féin, senior sources told The Irish Times.
It is understood that when Mr Blair met Dr Paisley at Downing Street yesterday he was unable to say whether the IRA would at the last moment agree to provide future photographic evidence of decommissioning.
Senior sources have stated that whenever Mr Adams or other senior Sinn Féin negotiators were asked whether the IRA would allow photographs to be produced, the consistent answer was that this was solely a matter between the IRA and the decommissioning body. Sinn Féin negotiators have not deviated from that position, they said.
Dublin and London, however, believe there is a reasonable possibility that, if the DUP demonstrates it is fully sharing power with Sinn Féin, that the IRA under the terms of its relationship with decommissioning chief, Gen John de Chastelain might then allow photographs to be produced. In terms of the visual proof issue today's meeting at Downing Street between Mr Adams and Mr Blair could be crucial.
Were Mr Blair to make a radical commitment to Sinn Féin such as major - rather than staggered - demilitarisation coinciding with IRA decommissioning, then Mr Adams might be prepared to ask the IRA to provide future photographic proof of decommissioning, one source indicated.
This was all in the realm of possibility, he stressed - there was no such offer in place at the time of writing. But in terms of Dr Paisley's demand for prior photographic evidence of IRA disarmament, Dublin and London are convinced there is no chance of this happening before the DUP delivers power sharing.
Sources characterised this issue as a dangerous brinkmanship battle between the DUP and republicans over who might "blink first".
However, they added that if the deal collapsed over Dr Paisley's demand for prior proof that if the governments then published their blueprint, the DUP would take the brunt of the blame for the failure of the deal.
"What is on offer from republicans is frankly incredible in terms of where we are coming from. If the proposals are published it certainly won't damage the Shinners, but I believe a ton of bricks would fall on top of Dr Paisley and the DUP," said a senior source last night.
"But it's not over yet, anything could happen in the coming days," he advised.