Boris Johnson has given his backing to police officers who threatened to arrest Tory chief whip Andrew Mitchell during an altercation in Downing Street.
The London mayor said the warning - disclosed in the official police log of the incident - showed the "gravity" of Mr Mitchell's conduct.
Mr Johnson's intervention again frustrated attempts by No 10 to close down the issue after days of damaging media coverage.
It came as a YouGov poll found more than two-thirds of voters - 69% - accepted the police account that Mr Mitchell called officers "plebs" after they refused to let him cycle through the main gates of Downing Street.
More than half the 1,739 adults questioned in the online survey - 52% - said they thought he should resign.
Cabinet Secretary Sir Jeremy Heywood has ruled out an inquiry into the incident arguing it would serve no purpose as the officer involved accepted Mr Mitchell's apology and did not wish to pursue the matter further.
However there was continuing anger within police ranks over Mr Mitchell's refusal to accept the officer's account of the incident, with the minister insisting he did not say the words attributed to him.
According to the 442-word police log - published in full in the Daily Telegraph - Mr Mitchell called officers "f****** plebs" and told them to "learn your f****** place".
The female officer who made the report said she warned him that if he continued to swear, she would have no option but to arrest him under the Public Order Act.
Mr Johnson, who has consistently argued that anyone who swears at police should face arrest, described the police action as "wholly common-sensical".