The Mayor of London, Ken Livingstone, is set to be cleared "on the balance of probabilities" of assaulting his partner at a party last year.
A lengthy investigation by the Standards Board for England, the local government watchdog, has also cleared Mr Livingstone of two further charges of pushing a man down a stairwell and of leaving the scene before the police arrived, according to the BBC.
The affair has hung over Mr Livingstone, 57, and his partner Emma Beal, 37, since last May. It was alleged that at a birthday party for Ms Beal's sister in Tufnell Park, north London, a drunken Mr Livingstone became involved in a fracas after manhandling his pregnant partner, accusing her of smoking.Her friend, Robin Hedges, 35, who works for the London Evening Standard, fell down a 15ft stairwell and received serious head injuries. He accused Mr Livingstone of pushing him.
Mr Livingstone denied the charges after being hauled before the London Assembly, maintaining that he had only had three glasses of wine and that Mr Hedges' fall had been an accident. But the Liberal Democrats still referred the matter to the standards board.
Its report, currently in draft form and likely to be published within the next month, says that "on the balance of probabilities" the Mayor should be cleared of all the charges. It adds that his explanation of events "was not misleading or untrue".
The report says there was evidence that conflicted with and supported the Mayor's version of events.
But the panel accepted Ms Beal's explanation that there had been no assault, adding that it was unable to "rule out the possibility that her evidence was affected by her wish to protect Mr Livingstone".
It also said there was nothing to support allegations made by Mr Hedges that Mr Livingstone had hit or pushed Ms Beal - who gave birth to a boy in December - in the stomach.