Earlier this week, I wrote that there was confidence in the No camp, concern among Trimble supporters. By last night the balance had shifted somewhat: there was qualified confidence on the Yes side, slightly less assurance in the No camp.
The shock result in the leadership election at the Ulster Unionist Council on March 25th may not be the best guide to what will happen tomorrow. Martin Smyth rattled the Trimble regime with a surprise tally of 43 per cent.
Two points may be worth making: first, this came a week after Mr Trimble's extremely controversial and politically risky - some thought suicidal - comments in Washington, indicating that he was prepared to go back into government with Sinn Fein without receiving IRA arms upfront. Second, Mr Smyth, a former grand master, may have garnered votes among the 120-odd Orange delegates on the basis of informal organisational solidarity, or indeed his affable personality, and there is no guarantee that such votes would go against Mr Trimble in the rather different context of the looming Waterfront meeting.
A tally of 57 per cent for Trimble in a "beauty contest" was considered a setback; even a small margin of victory for either side tomorrow would generally be seen as decisive. The mills of Ulster Unionism grind slowly but they grind exceeding small: it has taken years and even decades to get to the point that has now been reached but there is widespread agreement that we have arrived at a defining moment.
As always, there are last-minute occurrences that jar the nerves. Dissident republicans were blamed for what appeared to be a failed mortar attack on a British army base near Crossmaglen. The DUP annihilated the UUP and took a safe seat from it in a by-election to Banbridge District Council. Loyalist paramilitaries, who for some reason tend to get a more tolerant reception than their republican counterparts, were taking an obdurate stance on weapons.
There may be more: remember Harold Macmillan's strictures on "Events, dear boy" and the determining influence they can have on politics.
Nobody wants to invite disaster but it is clear that a "spectacular" by dissident republicans could unsettle the fragile consensus developing around Mr Trimble that maybe, just maybe, the IRA statement should be taken at face value.
Senior No campaigners said the public phase of the campaign was more or less at an end. They would not bother with meetings: their time would be much more profitably employed knocking on the doors of three or four old friends who were also UUC delegates. They would drink their tea, or perhaps something stronger, as they sought to persuade them that Trimble's way was not Ulster's way: this deal will lead us to perdition.
There has been a certain amount of differentiation in the No camp. Jeffrey Donaldson appears to have been trying to put clear blue water between himself and some of the more hardline elements. He was seeking a meeting with Mr Trimble today in an effort to prevent a damaging and rancorous debate at the Waterfront. Some observers felt the Lagan Valley MP was endeavouring to remind people that, although he walked out of the talks on Good Friday 1998, he had been there for the previous two years.
The faultline in the No camp seems to lie between those who may be willing to accept power-sharing, but cannot stomach Sinn Fein in government while the IRA remains in existence, and those who want majority rule within Northern Ireland and no truck with these dangerous schemes calculated to sap Ulster's will and bring about eventual Irish unity.
Nationalists and republicans are watching nervously. Whatever happens tomorrow, there will be the mother of all fightbacks to save the Patten Report on policing. The SDLP and Sinn Fein, with next year's likely general election in mind, will be seeking to outdo one another in detoxifying the Police Bill, due to be introduced in the Commons on June 6th. Seamus Mallon intends going through the legislation line by line. Sinn Fein, still abstentionist when it comes to Westminster, will rattle London's cage from outside.
Another source of anxiety, especially to republicans, is the possibility of a time-limited motion. The prospect of the UUP leadership making another conditional jump subject to decommissioning by a specific date would unsettle the IRA, and the political situation might well spiral out of control.
Although both Downing Street and the White House have rubbished the Guardian report claiming a rift between Bill Clinton and Tony Blair on RUC reform, republican and Irish-American sources maintain that the Prime Minister did seek to put pressure on the President to, in turn, twist Sinn Fein's arm to tolerate the notion of a subtitled police force: "The Police Service of Northern Ireland (incorporating the RUC)."
We may have to wait years for a definitive version of events to emerge but certainly there is a different view of the police issue in the US than there is of, say, the Orange Order's right to march. A cross-community police force is a sine qua non in the American, especially White House, scheme of things, whereas Americans have a more complex view of the marching issue and may not always be aware of the pressures on nationalists.
There is no evidence to suggest at this stage that significant concessions on policing to placate John Taylor are in the offing. In the first place, republicans say it would be a "deal-breaker"; second, Mr Taylor's importance has diminished in the past week, partly due to his hot-and-cold antics but also because Mr Trimble has definitively taken centre-stage.
Whoever is the leader of Ulster Unionism on Monday, there is no doubt who heads the party today.