YouGov surveyed more than 1,000 Conservative party members for the Times newspaper, finding 43 per cent of members backed Boris to be the next Tory leader, compared to just 22 per cent supporting the chancellor.
One per cent of party members polled said they wanted education secretary Nicky Morgan to succeed Prime Minister David Cameron as Tory leader.
The poll showed that Johnson's approval rating had benefited from his decision to back Brexit. YouGov asked party members who they supported for leader both before and after the mayor revealed that he wanted the UK to leave the EU.
Support for Johnson rose five points after his announcement, while Javid dropped by four points and May lost two points at Johnson's expense.