The public consider Boris Johnson the most likeable politicians in Britain but they do not believe he would make a better prime minister than David Cameron, a new poll suggests.
The Michael Ashcroft survey, which will make sobering reading for those Tory MPs who want to replace Cameron before the next election, shows that even Ed Miliband is considered a better potential prime minister than Johnson.
Just 29% said Johnson would be the best prime minister, next to 33% for Cameron and 31% for Miliband. Nick Clegg scored badly on seven per cent.
Only 35% of respondents said the London mayor would be capable of running the country as prime minister.
Ukip voters were the most sympathetic, with 57% saying the Tories would be better placed to win the election with Johnson at their head, although just 35% said this would affect their vote personally.
That Ukip support is surprising, given Johnson's liberal views on immigration, but it probably reflects his image as an outsider rather than an assessment of policy.
Twenty-three per cent of general respondents said they would be more likely to vote Conservative if Johnson was leader, compared to 50% who said it would make no difference.
The findings will come as a shock for the Conservatives who believe that a Johnson leadership would be a panacea for the party's problems.
"There is no doubt that Boris is a great asset to his party, and I think his time as mayor has shown that he is up to the demands of executive office," Ashcroft said.
"But ultimately, were it to come to pass, the fact of having Boris as leader would not make the things that stop people voting Tory go away."
Generally the poll showed that Johnson maintains his customary popularity with the public. Over half thought he was "different from other politicians, and in a good way".
Ninety-one per cent of people recognised photos of him - second only to Cameron on 94%