Boris Johnson's approval rating among political insiders has plunged 27 points in the last month, after a succession of poor decisions and damning headlines.
The survey of 100 leading political insiders was carried out by Politics Home in the days following the Ray Lewis fiasco and reflects growing doubts about his ability to be an effective leader of the capital.
Boris's approval rating amongst right-leaning panelists has dropped slightly but still remains high. However, the biggest drop was among left-wing and non-aligned panelists.
Significantly non-aligned members of the panel now rate him as a poor mayor by a margin of 60-40 with only four per cent of all panelists believing that he is doing a very good job as mayor.
The results come in advance of the first opinion poll on his performance so far which was carried out this week by Yougov. The results are expected later this weekend or early next week.