London mayor Ken Livingstone will face a disciplinary hearing over comments made to a Jewish journalist.
Ken Livingstone could be suspended from office
He will appear before an independent panel and could be banned from office for five years if it rules against him.
An inquiry began after Mr Livingstone accused a reporter of "doorstepping" him at a party in February and likened him to a concentration camp guard.
He faces allegations that he failed to respect others or that he brought his office into disrepute.
Mr Livingstone will appear before the independent Adjudication Panel for England some time before December which will rule if he breached the Greater London Authority Code of Conduct.
He could be banned from office, suspended, told to apologise, censured or told to go for training. It is thought that a five-year ban is unlikely.
It follows a confrontation between the mayor and Evening Standard reporter Oliver Finegold outside a party for MP Chris Smith.
The mayor accused Mr Finegold of pursuing him and on tape he was heard asking the reporter if he was a "German war criminal".
Mr Finegold replied: "No, I'm Jewish, I wasn't a German war criminal. I'm quite offended by that."
The mayor then says: "Ah right, well you might be, but actually you are just like a concentration camp guard, you are just doing it because you are paid to, aren't you?"
He later refused to apologise to the reporter, saying he was the victim of a 24-year hate campaign by Associated Newspapers, publishers of the Evening Standard and the Daily Mail.
But he said his words were not intended to cause such offence.
The Board of Deputies of British Jews referred the matter to the Standards Board for England, which has now referred it to the independent panel.
A spokesman for the Standards Board said the case had not been referred to the GLA's own standards committee because some elected members had already "expressed a view" that Mr Livingstone should apologise.
Mr Livingstone told BBC London on Tuesday: "The Standards Board has rejected the allegation that I failed to comply with the GLA's code of conduct in relation to this exchange.
"The tribunal will now consider the issue of whether I treated a journalist with respect."
But Graham Tope, Lib Dem leader on the London Assembly, said: "It is unfortunate that this whole sordid sorry little episode has had to go to the Adjudication Panel for England when the mayor could have eaten some humble pie and said sorry."