By Sean Curran
BBC political correspondent
Ken Livingstone has been suspended from office on full pay for four weeks for comparing a Jewish journalist on London's Evening Standard to a Nazi guard. Can London's mayor win the latest challenge of his political career?
The suspension is an embarrassment for Mr Livingstone
Ken Livingstone is one of the great survivors in British politics.
His opponents thought they'd seen the back of him when the Thatcher government abolished the Greater London Council (GLC) in 1986.
But Mr Livingstone did not fade into the background or retire to spend more time with his newts. Frequent appearances in the media - including a stint as a restaurant critic for the Evening Standard - helped him maintain his public profile.
The former GLC leader also swapped London's County Hall for the Palace of Westminster and embarked on a career as a Labour backbencher.
In 2000 he defied Prime Minister Tony Blair to stand as an independent candidate in the London mayoral elections.
He romped home and his first words in his new job were: "Now, before I was so rudely interrupted 14 years ago..."
By 2004, Mr Livingstone was back in the Labour Party. He started his campaign for a second term as London mayor as Mr Blair's candidate.
The surprise suspension from office - and the large legal bill - is an embarrassment for Mr Livingstone, but nobody expects him to give up without a fight.
He is expected to challenge the decision in the courts. Far from damaging the London mayor, the ruling could trigger a political campaign. Already it has all the makings of a constitutional row with "Red Ken" in the role of a defender of democracy.
He said in a statement: "Three members of a body that no-one has ever elected should not be allowed to overturn the votes of millions of Londoners."
Senior figures from the Labour movement have already voiced their support.
Tony Woodley, the general secretary of the Transport and General Workers' Union, described the suspension as outrageous.
"This harsh sanction hasn't been made in the interests of Londoners and is a menace to democracy," he said.
The mayor's critics insist the row is not about democracy.
A spokesman for the Evening Standard said the issue was Mr Livingstone's behaviour and his continuing refusal to apologise.
Mr Livingstone has always enjoyed his reputation as an outsider who doesn't play by the rules that restrict other politicians
The Conservative deputy chairman of the London Assembly, Brian Coleman, said Mr Livingstone's "complete failure of judgement and leadership" raised serious questions about his suitability for office and called on the mayor to seriously consider his future.
But it is clear that Mr Livingstone considers that his future is as London mayor.
He has turned previous battles to his advantage.
The arguments about the GLC and the first mayoral elections could have ended his political career but he saw off two of the leading figures of post-war politics - Margaret Thatcher and Mr Blair - without suffering any long-term damage to his popularity.
Mr Livingstone has always enjoyed his reputation as an outsider who doesn't play by the Westminster rulebook that restricts other politicians.