More details have emerged on British-Irish proposals to deal with the demand for visible decommissioning.
Decommissioning pictures would be held until March
Talks sources suggest that by the end of December, General de Chastelain could report that all IRA weapons have been "put beyond use".
Photographic proof of this would be held by the head of the Independent International Commission on Decommissioning until March.
There would then be a new power-sharing executive.
The details emerged as Sinn Fein and the DUP were preparing to receive the governments' responses to their queries over the governments' joint proposals aimed at restoring devolution.
The two governments have said they are ready to publish their proposals if the parties do not sign up to a deal.
The DUP's executive meets on Friday evening, while Sinn Fein leader Gerry Adams has met Tony Blair for further talks at Downing Street.
Insiders have told the BBC that the proposals from the two governments are very clear: if a deal is done, then, by the end of this year General de Chastelain would report that all IRA weapons have been put beyond use.
This would open the door to a shadow assembly at the start of January.
Two churchmen - agreed by the DUP and republicans - would witness the acts of decommissioning.
Sources say that under the governments' proposals, photographs would be taken, but would not be published immediately.
It is not yet known how much of this will be agreed to by the parties, although the DUP is saying no deal will be made without photographs.
BBC Northern Ireland security editor Brian Rowan added that "nothing was coming from republicans at this time to suggest that the IRA has agreed to this proposal".
A Sinn Fein spokesman said that republicans were not the sources of these reports and were unhappy about them.
DUP MP Jeffrey Donaldson said his party would not go into government with republicans unless transparent decommissioning had taken place.
Mr Donaldson added that he was confident they would reach agreement on the issue.
"We are closer than we have ever been. We are hopeful that we can close the outstanding issues, but we're not there yet," he said.
"I have to say that on the issue of 'no guns, no government' ... we have made significant progress on that front and I believe that we can close the gap."
At the conclusion of intensive political talks at Leeds Castle in Kent in September, Mr Blair and Mr Ahern said the thorny issues of IRA disarmament and future paramilitary activity appeared to be resolved.
But, the two governments were unable to get the Northern Ireland Assembly parties to sign up to a deal over power-sharing after unionists and nationalists clashed over future devolved institutions.