The mayor of London's senior aide Lee Jasper has resigned.
Ken Livingstone's race adviser blamed the "racist nature of a relentless media campaign" for his decision.
Mr Jasper had been at the centre of allegations over the misuse of public funds and was due before the London Assembly on the matter on Wednesday.
A Greater London Authority (GLA) statement paid tribute to Mr Jasper's work and said there was no foundation for the allegations against him.
The resignation comes after the Evening Standard newspaper published claims that Mr Jasper had sent intimate e-mails to a woman involved with organisations which received money from City Hall.
In a letter to the mayor, Mr Jasper said: "It has become clear that a number of matters which are not of first importance in London are being used to distract from the crucial questions in the election campaign.
"The racist nature of a relentless media campaign and the consequent effects on myself and family have placed an intolerable strain on all of us.
"I have decided to put a stop to this by tendering my resignation."
This vile little man's departure can only be considered cause for celebration. However, I wouldn't bank on his disappearance from public life being permanent: in the world of race hustling, scum always floats back to the top...
Update: Livingstone has responded to Jasper's resignation by saying that he hopes to reappoint Jasper some day in the future. As Harry's Place suggests, this day may well be the 2nd May, 2008. If Livingstone is re-elected on the 1st May, that is...