Now the jeers and heckles are louder as Democrats block the Republican diehard's appointment to the post of United States Ambassador to the United Nations, complaining that there are disturbing questions about his record as Under-Secretary for Arms Control and International Security that remain unanswered.

In addition, they say, his tart-tongued criticism of the UN and prickly temperament render him unsuitable for the US$179,900 UN post, and they liken him to a 'bull in a china shop'. It is a point on which even some Republicans have voiced agreement.

'No one's really excited about him going to the UN,' Republican Senator George Voinovich said. 'John Bolton is the poster-child of what someone in the diplomatic corps should not be.'

John Robert Bolton was born on November 20, 1948, in Baltimore, Maryland, to parents Virginia and Jack - a veteran of the Allied invasion of Normandy, France, four years earlier, who later became a firefighter. They had a daughter, Joni, nine years later.

Home was a modest, terraced house in the working-class neighbourhood of Yale Heights, but Mr Bolton won a superior education by clinching a scholarship at the city's McDonogh military school.

There, his interest in politics first emerged as he argued the merits of the Vietnam war with his left-leaning history teacher, their discussion often spilling over into the lunch breaks. When he left in 1966, the school magazine noted him for his conservative activism and his 'efficient, if sometimes controversial' management of its pages. Such was to become his trademark.

Despite backing the Vietnam war and joining the National Guard while at university, he never served there. 'I confess I had no desire to die in a Southeast Asian rice paddy. I considered the war in Vietnam already lost,' he said later.

In 1974, he emerged from Yale with a law degree and took a job as an associate attorney with the Washington law firm Covington & Burling, where he stayed for seven years before embarking on his career in government - first as a general counsel and then as a policy administrator at the US Agency for International Development, under former president Ronald Reagan's administration.

Noted for his dogged manner and brilliant intellect, and viewed as part of the emerging breed of 'new Right' lawyers, he was appointed assistant attorney-general in 1985 and, following the election of President George H.W.Bush in 1989, assistant secretary for international organisation Affairs at the State Department.

Mr Bush's failure to win re-election in 1992 brought a temporary halt to Mr Bolton's public service, but the success of his son, George W. Bush, at the 2000 presidential election revived it.

In May 2001, after another stint in private law practice and a period as senior vice-president of the American Enterprise Institute, a conservative Washington think-tank, Mr Bolton was sworn in as President Bush's Under-Secretary of State for Arms Control and International Security.

It was in that role, critics allege, that he tried to bully intelligence officials into conforming to his own - and the Bush administration's - unsubstantiated views relating to 'rogue states' such as Syria and Cuba and their ability to develop chemical and biological weapons.

In addition, they claim, he misused his position to gain access to secret information about individuals and corporations, for both personal and political reasons.

Until more light is shed on the matter, say Democrats, President Bush's nomination of Mr Bolton for the UN post cannot be approved.

His personal life has also come under scrutiny, though not from Congress. Larry Flynt, a notorious porn publisher, has made grubby allegations relating to Mr Bolton's relationship with first wife Christina, from whom he split in 1982, though the muckraking has failed to register on Washington's radar.

Mr Bolton is now married to Gretchen Brainerd, an accountant, and their daughter, Jennifer Sarah, has followed in her father's footsteps to study at Yale.

Mr Bush could appoint Mr Bolton unilaterally, but without congressional backing his reputation on the world stage would be seriously compromised.

His detractors say it already is and that his blunt-talking, abrasive manner will win America few new friends at a time when it could do with some. A militarist with a tendency towards the inflammatory rather than the diplomatic, Mr Bolton is a leading hawk on China policy and a straight-talking critic of North Korea (he once branded Kim Jong-Il a 'tyrannical dictator' on the eve of crucial talks. Pyongyang responded by branding Mr Bolton 'human scum').

But supporters say his tough-talking, no-holds-barred approach is exactly what is needed to bring change to a diplomatically crippled institution.

'If anyone can push the United Nations towards real reform, it is a serious critic like John Bolton,' says Doug Bandow, a senior fellow at the Cato Institute. 'The challenge for supporters of the UN is to change the organisation so that someone would notice if it were to lose 10 storeys.'

'There is no such thing as the UN ... only the international community, which can only be led by the United States'

Speech to a federalist forum, 1994

'Recognition of Taiwan would be [what] the region needs. The notion China would respond with force is a fantasy'

Enterprise Institute, 1999

'The UN Secretariat building in New York has 38 storeys. If it lost 10 storeys, it wouldn't make a bit of difference'

Speech to federalist forum, 1994

'Europeans can be sure America's days as a doormat for EU political and military protection are coming to an end'

Before US invasion of Iraq in 2003

'The UN should be used [as] we choose to advance American interests, not to validate academic theories'

Writing in a 1997 book