Boris Johnson has insisted he can broker a new Brexit deal with Europe because the political landscape has “changed”.
The leadership frontrunner said he could agree a new deal with the EU before the October deadline because there was now a "different understanding" of what is needed in the UK and in Europe.
In an interview with the BBC, he said: "I think actually that politics has changed so much since 29 March.
"I think on both sides of the Channel there's a really different understanding of what is needed."
Mr Johnson, who described Theresa May's deal as "dead", said he "did not believe for a moment" that the UK would leave Europe without a deal.
But he added that he would be willing to do so if that was required.
"My pledge is to come out of the EU on the 31st of October... but that is not where I want us to end up, it is not for a moment where I believe we will end up.
"But in order to get the result that we want the common sense thing to do is to prepare for a WTO exit."
Mr Johnson's interview came after police were reportedly called to the house he shares with his partner, Carrie Symonds, in Camberwell, South London.
He told the BBC he did not want to comment on reports, adding: "I do not talk about stuff involving my family, my loved ones.”
Mr Johnson previously argued that the UK should leave on October 31, with or without a deal, insisting this was “eminently feasible”.
He wrote in The Daily Telegraph on Monday: “We are going to focus all our efforts on honouring that single great promise — and we are going to come out of the EU on October 31.”
But, there has been some confusion over Mr Johnson’s plan to negotiate a free trade deal with Brussels in an implementation period after Britain had left the European bloc.
EU chiefs have warned that there would be no such period if no Brexit deal is struck and former International Development Secretary Priti Patel, an ally of Mr Johnson, stressed that the Withdrawal Agreement sought by Theresa May was “dead”.
Meanwhile, at a hustings of Tory members on Saturday, leadership rival Jeremy Hunt said that he would “100 per cent” leave the EU without a deal if an agreement was well out of reach come October 31, but has not tied himself to such a clear-cut Brexit day.
He has also warned that a government under Mr Johnson would rapidly collapse, paving the way for Labour to take power.
The new Prime Minister is expected to be announced on July 23 and to take office the following day after a final Prime Minister’s Questions by Theresa May.
Mr Johnson also defended his record as foreign secretary and mayor of London, pledging to be a politician "who sticks by what (he) believes in".
Apologising for upset caused by gaffes during his tenure, he said he did not enjoy offending people but also claimed the public deserve a prime minister who speaks their mind.
The politician has previously come under fire for his handling of the continuing incarceration of British-Iranian citizen Nazanin Zaghari-Ratcliffe, and when he labelled Burka-wearing Muslim women "letterboxes".
"What I pledge to, you know, and what I think the people of this country want to hear is, I will be a politician who sticks by what I believe in.
"Yes occasionally I may say things as I've said before, that cause offence, and I'm sorry for the offence and I'm sorry for the offence I caused, but I will continue to speak my mind because I think people deserve to hear what's going on in my head."
Asked for his response to being called a "coward" by his rival, Mr Johnson said: "Look you know I just always invoke the 11th commandment of Ronald Reagan which is 'thou shalt never speak ill of a fellow conservative'."