Mr David Trimble survived an effective leadership challenge from Mr Jeffrey Donaldson at a Ulster Unionist Council meeting in Belfast last night, but now faces a possible split in the Ulster Unionist Party.
Mr Trimble urged Mr Donaldson not to carry out his threat to walk away from the party. The Lagan Valley MP, however, refused to disclose whether he will leave the UUP and bring his supporters with him.
He appeared to spurn the olive branch from Mr Trimble who won last night's vote by 54 per cent to 46 per cent. Mr Trimble's margin of victory was 440 votes to 369.
After the count Mr Trimble appeared at a press conference with several of his supporters. Mr Donaldson, sounding and looking quite emotional, gave a press conference with only Enniskillen unionist Ms Arlene Foster beside him.
Mr Donaldson described the UUP leader's success as a "Pyrrhic victory". He said the 809 delegates had a choice of voting for "principles or a tactical approach to this process that has not served this party well" and ended up choosing tactics above principle.
Mr Donaldson will engage in a period of reflection before deciding whether to quit the UUP. He said he would not decide until after a no-confidence motion against him tabled by 70 members of the Lagan Valley UUP constituency association was taken towards the end of the month.
While Mr Trimble was sufficiently gracious to ask Mr Donaldson to remain in the UUP, he insisted that the MP must follow party policy.
The Taoiseach, Mr Ahern, last night congratulated Mr Trimble and said he would review the situation with the British Prime minister, Mr Tony Blair, next Friday on the margins of the EU summit in Thessalonika, Greece.
Mr Ahern said: "I look forward to continuing to work with Mr Trimble, his colleagues in the UUP and other pro-agreement parties to make sure that the various commitments and undertakings in the agreement are fully implemented.
"The Joint Declaration is a route map for that implementation and is the shared agenda of both governments. The Minister for Foreign Affairs will discuss progress on this and other matters when he meets the Northern Ireland Secretary of State in Dublin on Wednesday."
This was the twelfth UUC since the Belfast Agreement, and Mr Trimble said he felt like a heavyweight boxer who had fought many rounds and won each on points.
Mr Donaldson said the UUP's objectives were devolution and decommissioning, but " tonight we have neither".
"When I joined this party I joined because it stood for something. Because it had principles that I believed in. One of those principles is that the Irish Government should not have a say in internal affairs of Northern Ireland. Tonight I believe on that principle we have prevaricated."
He warned: "This leaves people like myself, and those who supported me, in a position where we have to decide if this party now represents what we believe in. Does it represent the principles of unionism? Is it capable of commanding the support of a majority of unionists in Northern Ireland.
"We will decide whether this party represents the best way forward for unionism, but I have to say to you very honestly the decision taken tonight leaves me with a very serious doubt about whether the Ulster Unionist Party represents what I joined it for - represents what the people who voted for me, voted for.
"I said that this was a defining moment for unionism. I believe it is. The consequences of tonight's decision will unfold perhaps in the days and weeks to come, not just in terms of what I and others do as far as this party is concerned but in terms of how ordinary unionist voters respond to this decision.
"Their confidence in this process has collapsed; any measure taken whether it be opinion poll or election poll demonstrates very clearly unionist confidence is at its lowest ebb. Tonight we had an opportunity to address those concernsand to say we are going to do something about it. But we chose not to do that."