Although David Trimble and Conor Cruise O'Brien may be on different sides over the Belfast Agreement, they do have one very striking feature in common. Both of their careers are prime examples of politicians seeking to apply intellectual criteria to their policies, decisions and actions.

It was noticeable that after his first meeting with Gerry Adams, Mr Trimble took time out to draw the attention of a bemused and deadline-conscious media at Stormont to the nearby statue of his predecessor as party leader, Sir James Craig, and to cite Craig's meetings with Michael Collins and Eamon de Valera as precedents for his own encounter with the Sinn Fein leader.

Mr Trimble also reminded Young Unionists of the precedent when he addressed their recent conference, his point being that, like Craig, present-day unionists should have confidence in their ability to respond to the political circumstances of the day.

In the same speech, Mr Trimble recalled that his decision to join the ultra-unionist Vanguard organisation, which flourished in the early 1970s, was made after he had read philosopher Karl Popper's book The Poverty of Historicism - no wonder a friendly commentator called him "the intellectuals' intellectual".

But Mr Trimble has a good sense of practical politics and, as a trained lawyer, tends not to close off all his escape routes over any particular topic. However, he has been so strident on the decommissioning issue that it will not be easy for him should he decide eventually to accept a compromise.

But compromise there will have to be, otherwise the Assembly will collapse and with it Mr Trimble's new job as First Minister. He would survive in the short term as party leader but would inevitably be gobbled up by the hard-liners in his own party, with Ian Paisley and Bob McCartney cheering from the sidelines.

But it would be political suicide for Mr Trimble to make a deal on decommissioning in advance of Saturday's UUP conference in Derry. He needs what spin-doctors - those fallen angels of the intellectual world - call "the halo effect" and that means giving nobody any grounds for accusing him of a sell-out.

The agenda will provide for an hour's debate on constitutional issues before Mr Trimble's speech. Some discontent will no doubt be expressed but even the Union First group is happy with Mr Trimble's stated position on decommissioning - as long as he sticks to it.

Mr Trimble's speech is expected to be relatively low-key - apart from some stridency on the question of weapons. His supporters know how important it is for their man to get a good reception so that he looks good before the world: there will be no need to crank up what Charles Haughey once called "the applause-meter". Although Mr Trimble and his fellow-unionists have been measured in their response to the Nobel Peace Prize, at least some of those present will reflect - perhaps privately - that it is nice to see unionism acquiring a more positive image in the pages and on the television screens of the world.

Tony Blair's separate meetings with Mr Trimble and Sinn Fein's Martin McGuinness did not produce a public breakthrough, nor had it been expected. The Big Push is more likely next week, with hints that the British Prime Minister may be planning to fly into Belfast in a repeat of his Good Friday role.

Given that Jeffrey Donaldson is in the US canvassing for investment in Northern Ireland and that a prominent Union First activist, Peter King, is not planning to attend the conference either, the likelihood of fireworks on Saturday would appear to be limited. Union First had planned a pre-conference meeting in Belfast tomorrow night but this has now been postponed.

Under these circumstances, it would be farfetched to say that Mr Trimble's leadership is in jeopardy. By taking such a strong stance on decommissioning, he has managed to keep his hard-liners in check.

A successful conference will give him more freedom to manoeuvre and allow him to explore the various options being floated as a means of breaking the logjam.

Although SDLP sources were keen to stress that the proposal by their Assembly Member, Joe Byrne, for a "stocktaking" exercise on paramilitary weapons was not an official party position, it is certainly a good example of the type of ideas being mooted at present. SDLP sources said the party was not prescribing how the paramilitaries should deal with decommissioning but it was essential that Sinn Fein and the loyalist parties fulfilled the requirement in the Good Friday document to work "constructively" with Gen de Chastelain's decommissioning body. SDLP sources also questioned the tactical wisdom of Sinn Fein's constant calls on Mr Trimble to face down the anti-agreement forces in the UUP.

One Trimble supporter remarked that some party hard-liners had made a tactical error by seeking, not just decommissioning by instalments, but a whole series of measures, including the disbandment of the IRA, before Sinn Fein could be admitted to government. "If they positioned themselves an inch to the right of David, they would get a lot of support, but they are six miles to the right of him." This has had the ironic effect of strengthening the republican movement, whose spokes men have been able to argue that the decommissioning demand is part of a wider, anti-nationalist agenda.

As long as Mr Trimble maintains his strong stance on decommissioning, his leadership will not be in any serious jeopardy. The difficulty will come if he moves towards a more pragmatic position, as the logic of the situation dictates he should. It requires only 60 signatures to convene a meeting of the Ulster Unionist Council, the supreme governing body of the party. But if the compromise is sufficiently clever and can be presented as, in fact, a victory for Mr Trimble - much as he presented the Belfast Agreement - then who is to say that he will not secure a renewed endorsement of his strategy by the party faithful?

The mood among the unionist community is mixed and divided, which is hardly surprising given that unionist voters were split 50-50 in the referendum. But there appear to be significant numbers of ordinary unionists who, despite many irritations, would like the Assembly to continue in existence, want the cease-fires to hold and believe both of these factors outweigh the importance of securing the token destruction of weapons and explosives - which could be replaced next day in any case.

While the nationalist parties and the two governments will be disappointed if the October 31st deadline for establishing the North-South bodies is not met, the UUP is largely indifferent. Christmas will be more than time enough for it. However, Mr Blair and Mr Ahern, who have invested heavily in the process, will want the minimum of slippage. With John Hume and Seamus Mallon due to meet Mr Blair today, the pace of events is quickening. As one UUP dissident put it: "The train is rapidly approaching the buffers and it's a question of who pulls the communication cord first."