Gerry Adams is taking a gamble that his own side will keep the faith and that Paisley will deliver, writes Gerry Moriarty, Northern Editor.
Gerry Adams looked and sounded tired yesterday. Long, late hours of hard, grinding negotiations through Christmas accounted for that weary appearance, but there were other reasons too. His policing call was as big a political judgment as he has made in recent years: one of his biggest calls, in fact. It took a personal and emotional toll.
He admits as much in an interview with Dan Keenan in today's Irish Times. "No one should under-estimate how big a step this is both at a personal and political level," he said. "This is bigger than Sinn Féin, bigger than me, and bigger than the DUP," he said.
And it is. In terms of the broad canvas of the political process, policing, after an end to the killing, was always the biggest prize to be won. Sinn Féin endorsing the PSNI meant the war was over and that for this generation of republicans there was no going back. It meant that Northern Ireland had a chance to function as a relatively normal society with a government and a generally acceptable police force and courts system. That hasn't happened yet, but Sinn Féin supporting the police has never been closer. Mr Adams must get a motion to that effect through his ardchomhairle by a two-thirds majority at Dublin airport this afternoon.
That should be possible. It should also be possible to sell it to an ardfheis, if a number of other issues fall into place. But there are no guarantees.
Mr Adams has a fallback position if this doesn't work. He is holding an ardchomhairle meeting today to sanction an ardfheis for some time in January. But the ardfheis will only happen if, particularly, DUP leader Ian Paisley upholds his end of an undeclared bargain.
If Dr Paisley can't or won't ease the path to policing for Sinn Féin in the coming weeks, then the ardfheis won't happen.
Nonetheless, the bottom line is that this is a huge gamble for the Sinn Féin leadership, and especially for the Sinn Féin president. At other key moments of the process, Sinn Féin always seemed to hold the trump cards, but this time Mr Adams is taking a leap of faith that his own side will keep the faith, and that he won't be left isolated by Dr Paisley. Policing is his last big card.
So, why now? "Because it is the right thing to do," Mr Adams said repeatedly yesterday. In his statement, in his interview with The Irish Times, in several print and broadcast interviews as well, these were the words on which he concentrated, to which he kept returning, "It is the right thing to do".
His detractors will argue that it was the right thing to do much earlier, that if he had followed the line of the SDLP on policing, or moved earlier on major issues like decommissioning, the prospect now would be for an Ulster Unionist first minister rather than Dr Paisley sitting in Stormont with Martin McGuinness as deputy first minister.
But we are where we are. And it's a place that can't be comfortable for Mr Adams, notwithstanding his stated determination to see this through. Policing is a hugely emotional matter for republicans.
Dissidents, who have threatened to kill Mr Adams and other Sinn Féin leaders, will try to exploit this issue. There will be Sinn Féiners who will be unable to stomach the party endorsing the PSNI. Some may defect from the party, others may simply walk away.
It's a gamble, too, in that for this to work DUP leader Dr Paisley must follow an unwritten but clearly understood script. At the very least he must be mindful that his words and actions can wreck the chances of this succeeding. His initial response yesterday was guarded, but, in DUP terms, positive.
He welcomed Mr Adams's statement, but said it must be tested to ensure he follows through on the policing promise.
Dr Paisley won't be able to keep all his troops in verbal check, it would seem. MPs Nigel Dodds and the Rev William McCrea have already stirred the pot over Christmas, and may do so again in the critical weeks ahead. But it is vital that Dr Paisley dictates that he alone is leader, and that with republican delivery he too will deliver.
It is important too that his key lieutenants, such as Peter Robinson, play their part in minimising the mischief of those in the party who don't want a deal.
The British and Irish governments remain convinced that deep within his psyche Dr Paisley wants this chance to work, and that he will be careful in trying to manage his constituency, whatever about controlling it.
The key issue over recent weeks of talks was ensuring a deal that would provide a model and a timeframe for transferring policing and justice powers to a restored Executive. It seems we have the model, and the hope is that with goodwill from the DUP and Sinn Féin, the timeframe will be sorted out.
Mr Adams, as is his wont, got quite sharp with The Irish Times a few weeks ago when he was asked would an SDLP or Ulster Unionist minister or ministers - rather than a DUP or Sinn Féin minister or ministers - running a department of justice be a compromise solution.
Yet that is the formula that was devised at the talks. Under the proposal it would be impossible for either Sinn Féin or the DUP to take the ministry, up until 2011 at least, so therefore it is likely that a senior and junior minister from the UUP and SDLP would take the department.
But lest we get ahead of ourselves, what happens at the ardchomhairle today is also critical to whether the sequenced St Andrews Agreement, which is due to lead to the restoration of full devolution by March 26th, is achievable.
The ardchomhairle will decide, on Mr Adams's suggestion, the wording of the motion on policing to be put to the ardfheis in January.
What was vital was that the wording was clear, explained a senior London source yesterday. The motion, he said, should embrace "support for the PSNI, support for those who go to the PSNI, and support for the courts". If that happens this afternoon, then a historic deal between the most bitter of opponents is realisable.