There is no doubt that the Sinn Féin leadership wants to make the commitment on policing, and that the DUP leadership wants to share power, writes British prime minister Tony Blair.
The biggest problem in the Northern Ireland peace process has always been the understandable reluctance of one side to believe the other's good faith. I have lost count over the years of the number of times one or other side has said to me that they believed in the process but the others weren't serious.
In particular, I recall time and again being told that the IRA would never decommission; they would never give up violence; they would never commit to exclusively peaceful means. But they have done all these things. Sinn Féin has demonstrated one of the most remarkable examples of leadership I have come across in modern politics. It has been historic and it has been real.
For republicans, whose experience of policing has been bitter and, in their eyes, deeply partisan, and who have spent a lifetime fighting it, a move to support the PSNI and the criminal justice system is a move of profound significance.
Of course, in one sense, there should be a commitment to supporting the police irrespective of any wider political progress. But given the particular and troubled circumstances of Northern Ireland, where one part of the community has a legitimate aspiration for a united Ireland, it is hardly surprising and is certainly understandable that it matters to them whether there is a proper, devolved system of accountability and government in place. It is then so much easier to make the case for full support for the police when the responsibility for oversight is in local, not British government, hands.
So it matters deeply to republicans that they know this support is being offered in the context of an agreement to share power.
St Andrews provided the basis for such an agreement. It stated that provided there was the commitment to the police, the courts and the rule of law as set out in paragraph 6 of the agreement, there should be elections, followed by a power-sharing executive, on March 26th, 2007 and the devolution of criminal justice and policing powers by May 2008. Since then, Sinn Féin has moved first to accept the pledge of office; then to a model for devolution; then to the ardchomhairle motion to change fundamentally the Sinn Féin position to one of support for the police.
They need to know clearly that if they do make this move - if they hold their ardfheis by the end of January, pass the ardchomhairle motion and, as they say they will, immediately go out and actively encourage everyone in the community to co-operate fully with the police and criminal justice system in tackling crime in all areas - then unionism will not be found wanting.
My assessment from the detailed conversations I have had with the DUP is that, provided there is delivery of the Sinn Féin commitment, they will enter into government with Sinn Féin on March 26th and they will accept devolution of policing and justice powers in the timeframe set out in the St Andrews agreement or even before that date.
Personally, I think any other outcome would be wrong, unfair to all sections of the community in Northern Ireland and a complete waste of a one-off, once-in-a-generation opportunity to make a lasting peace.
Given that the first such minister in the executive will not, in all likelihood, be from either the DUP or Sinn Féin, it really would be utterly unreasonable not to have devolution of policing and justice by May 2008, provided of course that the conditions for it are met.
Should all of this fail, it will be a bad blow, all the worse because it will be pointless. There is no doubt in my mind that the Sinn Féin leadership wants to make this commitment, or that the DUP leadership wants to share power. If either Sinn Féin or the DUP defaults now, it would be a crazy denial of what is, in fact, a shared intent.
All failure means is that, as the St Andrews agreement sets out, we move ahead on the basis of the new British-Irish partnership arrangements to implement the Belfast Agreement. But these will only ever be second-best and would require the same support for the police being sought and the same need for accountability being met. In other words, you would come back to the exact same issues, just in a much less benign environment.
So over the coming days, there will be republicans convinced that the DUP never really means to share power. They will ask what the point is of an ardfheis.
There will be unionists who will seize on any hesitation to say we told you so: Sinn Féin was never serious about changing policy on policing. Both will be wrong. But if we don't get action - the ardfheis on one side, power-sharing on March 26th on the other - we will never know.
Strong leadership has brought us this far. It can bring us further. Ten years ago the very idea of the DUP and Sinn Féin in government together would have been thought absurd. Today it can happen, indeed should happen. In 10 years' time, if it does, people will wonder why it was ever in doubt.
This is called progress and we should never give up on making it.