Mr Johnson said he would participate in a BBC debate on Tuesday night, after the second ballot of Tory MPs, but was accused of running scared from Rory Stewart and Dominic Raab, the two candidates who are most likely to be eliminated next week.
Taking part in his first live media interview of 2019 yesterday, the former Foreign Secretary said it would be “slightly cacophonous” and lead to “blue on blue action” if he joined a debate before the leadership field had shrunk further.
And Mr Johnson provided a conclusive answer to questions over his past drug use after days of speculation, saying that reports of him having taken cocaine related to “a single inconclusive event that took place when I was a teenager and which I have extensively described”.
Appearing on BBC Radio 4’s World At One programme, Mr Johnson said it was “important that we have a sensible grown-up debate”.
But he added: “My own observation is that, in the past, when you’ve had loads of candidates, it can be slightly cacophonous, and I think the public have had quite a lot of blue-on-blue action, frankly, over the last three years.”
Earlier, Mr Johnson’s top challenger, the Foreign Secretary Jeremy Hunt, called on his predecessor to “a little bit braver” and join the Channel 4 debate.
“What would Churchill say if someone who wants to be prime minister is hiding away from the media?” Mr Hunt told the Today programme.
All the other candidates in the race signed a joint statement pledging to take part in all televised debates, saying the leadership contest was “a critical moment” for the country and the party.
“The next Conservative leader, and prime minister, will have the crucial task of uniting Britain behind a new vision – not only to deliver Brexit, but to define what comes next,” they said. “This leadership contest provides an important opportunity to debate, to shape and to define the ideas which will underpin those competing visions. That is why we are committed to taking part in the Channel 4 televised debates this Sunday and the BBC programme next Tuesday.”
A spokesman for the Rory Stewart campaign said the next Tory leader had to “win back old voters and win over new audiences”, and shouldn’t turn down opportunities to set out their vision. “Any candidate who seeks that mantle can hardly opt out of a public debate,” the spokesman said. “If any candidate ducks that duty, there is a simple question we should ask: ‘What have you got to hide?’”
Channel 4 said there will be a “lectern available” if Mr Johnson changes his mind about not appearing in its debate. A spokesman for the broadcaster said in a statement: “We are disappointed that Mr Johnson will not be taking part in the debate to face members of the public for full scrutiny alongside the other candidates.
“There will be a lectern available if he changes his mind.”
On Brexit, Mr Johnson told the BBC it was “perfectly realistic” to renegotiate the Withdrawal Agreement to allow Britain to leave the European Union in October.
“There is a clear way that the now effectively defunct Withdrawal Agreement can be disaggregated - the good bits of it can be taken out.”
Mr Johnson said the “fundamental flaw” in the current Withdrawal Agreement is the Irish backstop, and claimed that a solution could be found.
“In the meantime, it’s absolutely crucial to prepare for no-deal and I don’t share the deep pessimism of some people about the consequences of no-deal,” he said.
“That’s not to say that I don’t think there will be some difficulties that need to be addressed and we must make sure that we can address them.”
Asked how he would solve the border problem, he said: “Those problems are easily capable of solution, as I think the Commission has said, in the past with maximum facilitation techniques and, after all, at the moment you already have goods conforming to different standards.”
Mr Johnson also defended his record as foreign secretary, including his handling of the case of British-Iranian mother Nazanin Zaghari-Ratcliffe, who is imprisoned in Iran.
He wrongly said Ms Zaghari-Ratcliffe was “training journalists” in Iran, a claim put forward by the Tehran regime.
“If you point the finger of blame at me... then I think you are unintentionally exculpating the people who are really responsible and that is the Iranian [Revolutionary] Guard,” he said.