Mr David Trimble today vowed to fight to remain Ulster Unionist leader as the clamour for his head grew.
Mr Trimble said he would be urging the party's membership to back him at their annual general meeting later this month when a bid to oust him could be launched from the party's anti-Belfast Agreement faction.
He said: "As always my position is up for re-election. I will be offering myself again for that position and if anyone else from within the party wishes to challenge me so be it.
"That is the democratic wish and mandate of the party."
Mr Trimble has come under mounting pressure after his party's MPs were cut from nine to six at the General Election.
Striking a defiant note, however, he declared: "I'm not scared of a challenge. I have been absolutely open with the party through this process."
Repeating his insistence that he would resign as First Minister on July 1 if the IRA failed to put its weapons permanently beyond use, he told BBC's On The Record that Ulster Unionists must "hold their nerve".
But newly elected North Belfast MP Mr Nigel Dodds, of the DUP, said Mr Trimble was now living on borrowed time.
"Trimble has basically run out of credibility and he is now running out of votes. The writing is on the wall."
Mr Dodds was one of three DUP candidates to snatch Westminster seats from the UUP as it increased its own contingent to five.As the Taoiseach and British Prime Minister Mr Tony Blair spoke today by telephone to arrange a meeting this week to work out plans for cementing the peace process, Mr Dodds said a complete overhaul of the Belfast Agreement is needed to appease the majority of unionists who now oppose the deal.
"No matter how they describe it, the reality is there's going to have to be a fundamental look at the basis on which this process operates.
"It enjoys the support of nationalists but it doesn't enjoy the support of the clear majority of unionists and it can't have stability on that basis," Mr Dodds said.
PA