John Bolton was picked as US envoy to the United Nations against a tide of Democratic opposition - and the unease, too, of the odd Republican.
Mr Bolton's UN tenure was controversial from the outset
After months of wrangling, President George W Bush forced through his choice in August 2005, by using a type of emergency measure known as a "recess appointment".
But Democratic gains in the mid-term elections made it inevitable Mr Bolton would not be confirmed in the post when the appointment expired in January 2007 - and so, a month beforehand, it was announced he was stepping down.
Mr Bolton's admirers call him a bright, hard-working realist whose scepticism about the UN's role made him an ideal envoy.
But detractors of this Bush administration hawk say his long-time criticism of the UN goes a long way past healthy scepticism.
More than 10 years ago, he famously said there was "no such thing" as the UN and called the US the world's "only real power".
He also declared that if the 38-storey UN building "lost 10 storeys today, it wouldn't make a bit of difference".
With his tousled appearance and trademark moustache, the 58-year-old Mr Bolton cut a charismatic figure.
Critics allege that while under-secretary of state for arms control, Mr Bolton:
Bullied and browbeat his underlings
Misused his access to intelligence
Undermined then Secretary of State Colin Powell
A Yale University-educated lawyer, he served in the administrations of both Ronald Reagan and George Bush Senior.
In 2000, he played a key role representing George W Bush in the presidential election recount - and was rewarded with the job of Washington's top arms control official in May 2001.
In this capacity, he was sharply critical of countries like North Korea and Iran.
In July 2003, he condemned North Korea's Kim Jong-il for living like royalty, while for millions of his people, life was a "hellish nightmare".
Pyongyang was incensed, labelling him "human scum" and refusing to continue negotiating with him.
Mr Bolton won widespread praise for his work establishing the Proliferation Security Initiative, a voluntary agreement supported by 60 countries which attempts to interdict shipments of fissile material.
But critics allege that while under-secretary, Mr Bolton misused his access to intelligence and undermined then Secretary of State Colin Powell.
There have also been accusations he tried to get two intelligence analysts who refused to tailor their assessments to his claims sacked. Mr Bolton denies the accusations, saying he merely clashed with the analysts over their "unprofessional" conduct.
The refusal of the White House to release the names of US officials whose communications Mr Bolton allegedly had monitored further stoked Democratic convictions that he has something to hide.
More damage was done when the state department was forced to acknowledge Mr Bolton had been interviewed as part of an investigation into intelligence lapses in the run-up to the Iraq war. Mr Bolton originally told Congress he had not.
Mr Bolton's appointment came when several figures on the American right were demanding root-and-branch reform of the UN, an organisation they see as emblematic of multilateral diplomacy at its most flabby and stultifying.
He led the successful campaign against the US ratification of the statute of the International Criminal Court (a product of "fuzzy-minded romanticism") and has been a blunt critic of disarmament treaties or negotiating with "rogue states".
"I don't do carrots," Mr Bolton is quoted as saying.
Analysts say that during his tenure at the UN, Mr Bolton was a tenacious, outspoken and at times counterproductive advocate of US efforts to prevent Iran from getting a nuclear weapon, push Syria out of Lebanon and bring African peacekeepers into Somalia.
Mr Bolton was seen as very effective on North Korea, pushing a strong sanctions resolution through the UN Security Council within days of Pyongyang's 9 October nuclear test.
Yet other diplomats at the UN have privately criticised Mr Bolton's abrasive style.
His tenure was a controversial one from the outset.
The nomination of such a strident character as UN envoy incensed many former US ambassadors - 102 of whom signed a letter urging senators to reject his nomination.
His supporters insisted he was right for the post, one - Frank Gaffney of the Center for Security Policy - saying he could offer "a dose of tough love to an organisation very much in need of it".