The Unionist leader's victory means that by tomorrow afternoon he is likely to be chief minister of an executive which will include Sinn Fein's Martin McGuinness as well as Paisleyite representatives.
But the manner of the victory has raised difficult political problems. The Ulster Unionist Council, the party's ruling body, backed Mr Trimble by 480 votes to 349, which at 58 per cent was regarded as on the low side for such a momentous decision.
It indicates Mr Trimble leads a divided party which harbours serious doubts about going into government with Sinn Fein, even on a trial basis. Already one MP, Willie Thompson, has resigned in protest. To win the vote he made a series of concessions to which Sinn Fein took immediate exception, arguing they went against the understanding that IRA decommissioning would take place on a voluntary basis.
The Unionist Council is to be reconvened in February for what was described as a final decision. Mr Trimble was said to have signed a post-dated letter of resignation: this was seen as in effect an ultimatum to republicans that if they did not deliver decommissioning by then the party would pull the plug on the fledgling executive.
The substantial anti-Trimble vote came in spite of a change of mind by his deputy, John Taylor, who at the last minute lent his support following "private and confidential assurances" from Northern Ireland Secretary Peter Mandelson. "I am now reassured that Unionists will not be trapped into a system of government with Sinn Fein without IRA decommissioning."
But there was much bitterness after the vote. William Ross MP, said the party had betrayed the people of Ulster, "and I think that the people will exact a very ferocious revenge". Cooler heads felt the anti- Trimble faction would fare better in February They believe the IRA will not have de-commissioned at that stage, leaving Mr Trimble with little choice but to resign.
But Mr Trimble, who was congratulated by Tony Blair and by the Irish government, said the party had given a clear endorsement to his proposals, which meant decommissioning would follow soon after devolution. Addressing the Sinn Fein president he declared: "We've done our bit. Mr Adams, its over to you. We've jumped - you follow."
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