Boris Johnson has again dodged questions over whether he intends to re-enter Parliament, following a poll which found that London voters think he should quit as the city's Mayor if he wants to stand as an MP.
The survey for the Evening Standard found that just 37% of voters in the capital (down from 43% in October 2013) thought it would be reasonable for Mr Johnson to combine the two jobs, while 43% (up from 39%) felt he should wait until after his second term at City Hall ends in 2016 before making a bid for Westminster.
The poll came amid speculation that Mr Johnson may be considering seeking selection as candidate for the safe Tory seat of Uxbridge & South Ruislip, in west London, after sitting MP Sir John Randall announced that he will stand down at next May's general election.
A return to Westminster would clear the way for Mr Johnson to stand in any future leadership election to replace David Cameron.
Mr Johnson was challenged over his intentions three times during an interview to promote proposals for a toll on diesel cars in a new ultra-low emission zone due to be introduced in central London from 2020.
But he repeatedly ducked the issue and tried to turn the discussion back to air quality standards, at one point even asking BBC Radio 4 World At One interviewer Edward Stourton "What sort of car have you got?"
Asked for his response to the poll, Mr Johnson said: " I'm getting on with my job as Mayor of London delivering the ultra-low emission zone."
When Stourton pressed him "Would you stand down as Mayor?", Mr Johnson replied: "I will certainly make sure that whatever happens we will have the ultra-low emission zone."
And asked a third time "Will you stand down if you stand as an MP?" he continued: "What I can tell you is that I will deliver my mandate as Mayor of London and I will continue to promote the ultra-low emission zone and you won't feel a thing. What sort of car have you got?"