Tory leadership contender Jeremy Hunt has refused to guarantee that the UK will leave the EU before Christmas, but said he “expects” it to happen by then.
He would not say when Brexit would take place if he became PM, telling the BBC: “I’m being honest with people”.
Rival Boris Johnson said the UK would leave by 31 October “come what may”.
He also defended his remarks on the UK ambassador in Washington, who quit this week over leaked criticisms of Donald Trump.
Mr Johnson added he did not accept that his failure to support Sir Kim Darroch during a debate on ITV earlier this week had prompted him to resign.
However, he said a “misrepresented” account of his remarks later relayed to Sir Kim had been “a factor” in his decision to step down.
He added: “I stood up completely for the principle that civil servants should be allowed to say what they want to their political masters.”
Up to 160,000 Conservative Party members are voting for their next party leader – and UK prime minister – to replace Theresa May.
The BBC’s Andrew Neil has interviewed both contenders for a programme broadcast on BBC One.
Mr Johnson, a former foreign secretary and mayor of London, is seen as the frontrunner in the contest.
Mr Hunt warned party members not to “vote with their hearts instead of their heads”.
He added that the “quickest way” to leave the EU was “to send to Brussels a prime minister who can negotiate a deal that will get through Parliament – and I’m that person”.
Foreign Secretary Mr Hunt, who set up his own business before entering politics, was challenged on whether he had the skills to negotiate effectively with the EU.
He replied that being an entrepreneur had given him the “basics”, adding: “In government those same skills I used to negotiate very complex things – like the licence fee deal with the BBC, the NHS pay awards, the protracted dispute to try and get a peace process going in Yemen – that business of negotiation is something I have been doing all my life.” Read more