Mr Donaldson, the MP for Lagan Valley since 1997, has carried the standard for the anti-agreement camp within the party ever since he staged a dramatic eleventh-hour walk out of the political talks of 1998.

Real peace is not just the absence of violence but the absence of the threat of violence.

Jeffrey Donaldson, New Year Statement 2000

His strong and continuing disagreements with his leader have led to Mr Trimble accusing him of launching a "full scale assault on the party" by pushing for destabilising meetings of the party's ruling council to decide the question of participation in Stormont.

No guns no government

Mr Donaldson's dissident status began when he refused to accept the UK Prime Minister Tony Blair's assurances over paramilitary decommissioning, and told Mr Trimble that he could not back the Good Friday Agreement.

Mr Donaldson then made it clear he was not prepared to enter power-sharing bodies with republicans unless he was certain that IRA guns would actually be handed over.

Later, in a gesture that caught the attention of the world's media, Mr Donaldson dramatically tore up the 1995 Framework Document in front of television cameras.

While the party blocked him from standing in the subsequent assembly elections, his stance won him the support of many UUP members who were becoming increasingly unhappy with the direction taken by David Trimble.

The publication of the Patten report, whose reforms on policing are opposed by many unionists, as well as the anti-agreement DUP's victory in the south Antrim by-election have only confirmed Mr Donaldson in his views that too much ground has been given by the unionists in the peace process.

It is clear for many of us that the IRA statement does not provide the clarity and certainty that Ulster Unionists need

26 May, On the IRA arms offer

Taking the initiative in attempts to bring his party out of the executive, Mr Donaldson put forward his alternatives to Trimble's strategy of working within the assembly in a letter to the UUP's governing council ahead of the critical meeting in October 2000.

Leadership challenge?

There have been attempts to ease tensions since they arose in 1998 and Mr Donaldson did resume work alongside his party leader on the sensitive arms question, for a while.

Despite this he has continued to be at the centre of speculation about a possible leadership challenge.

The speculation reached such a point that in July 1999 he went on the record to explicitly deny that he was planning a campaign and affirmed their friendship.

But when Martin Smyth MP, a member of the no camp, challenged Mr Trimble in March 2000, he was widely regarded as a stalking horse for a candidate waiting in the wings - and for many people that person was Jeffrey Donaldson.

Days before the May 2000 UUC meeting, he publicly stated again that there would be no leadership challenge.

As well as opposing power-sharing, the Lagan Valley MP has consistently said that the issue of prisoner releases and arms decommissioning were inextricably linked in the Northern Ireland peace process.

He described the release of the IRA man jailed for the killing of Lord Mountbatten as "premature" and has maintained that there should be no government with Sinn Fein without IRA arms decommissioning.

Young politician

Born in December 1962, the oldest of five boys and three girls, Jeffrey Donaldson was brought up as a Presbyterian in rural Kilkeel in County Down. He is married with two daughters.

He has described his own childhood as being "shattered" by the Troubles, most significantly the murder of a cousin who was a member of the Royal Ulster Constabulary.

Jeffrey Donaldson joined the Orange Order at 16 and began his political career when he joined the Young Unionist movement.

He went on to chair the Ulster Young Unionist Council in 1985 and 1986, and in 1983 he was appointed agent to the late Enoch Powell.

He entered the failed Northern Ireland Assembly of the 1980s as one of its youngest members and became heavily involved in the Unionist movement in the United States, often joining his party's delegations to President Bill Clinton in Washington.

Away from the main political front, the MP has held the trade and industry brief for his party and has played a prominent part in trade missions abroad.

Many nationalists regard Mr Donaldson as the voice of immovable unionism, refusing to compromise or accommodate other traditions.

Mr Donaldson has a simple reply: "People may wish to blame us but we have no illegal weapons."