He signalled his intention to run in the leadership contest, expected this summer, when quizzed about his ambitions at a business conference in Manchester. Mr Johnson spoke out as senior Tory backbenchers warned the Prime Minister that she is almost certain to face a fresh attempt to force her out of office next month. Bookmakers last night made Mr Johnson, a star of the Leave campaign in the 2016 EU referendum, the favourite to triumph in the race for the Tory crown. Betfair moved his odds to 11/4 from 7/2 after his declaration yesterday.
Mr Johnson stated his aim in response to being put on the spot during a question-and-answer session at the British Insurance Brokers’ Association conference.
He was asked: “You want the job, yes?” Mr Johnson was quiet at first, then said: “I’m going to go for it, of course I’m going to go for it.
“I don’t think that is any particular secret to anybody. But there is no vacancy at present.”
He joined former Cabinet minister Esther McVey and newly-promoted International Development Secretary Rory Stewart in openly declaring an interest in Mrs May’s job.
Work and Pensions Secretary Amber Rudd has also declined to rule herself out.
Other potential candidates include former Brexit Secretary Dominic Raab, Foreign Secretary Jeremy Hunt and Home Secretary Sajid Javid.
Some Tories believe Environment Secretary Michael Gove, who sabotaged Mr Johnson’s last attempt to stand for the Tory leadership by pulling out of his team on the day of his campaign launch to stand as a rival himself, is also considering entering the race.
Supporters of Mr Johnson expect him to put his record as a proven election winner at the heart of his pitch for the job.
One backer said: “He beat the Left twice in London when he defeated Ken Livingstone to be London mayor.”
A minister said: “We are at risk of getting slaughtered at the next general election.
“Polls consistently show Boris is the one Conservative who can beat Jeremy Corbyn.”
Allies say Mr Johnson’s campaign will focus on an “optimistic vision for the party and the country” with his enthusiasm for Brexit allied to traditional “One Nation” Tory values.
Mr Johnson has recently focused on commitments to increase funding for the NHS and tackle violent crime.
He is also seen by supporters as a future leader who could neutralise the growing threat to the Tories posed by Nigel Farage’s new Brexit Party.
His long record of championing a clean break from Brussels, from heading the Leave campaign to quitting the Cabinet in protest at the Brexit plan unveiled by the Prime Minister, will appeal to many anti-EU party members.
The growing pressure on Mrs May to quit intensified yesterday, with her former Downing Street adviser Nick Timothy saying: “Her premiership has failed, her authority is shot.
“We need to end this national humiliation.”