JEREMY Hunt clashed repeatedly with Boris Johnson as he challenged his rival over whether he would be prepared to resign if he failed to take Britain out of the EU on October 31.

In the only and only live TV head-to-head debate before a studio audience, the two would-be prime ministers squared up to each other in at times testy exchanges.

The Foreign Secretary went onto the offensive quickly. He launched the first of several personal attacks on Mr Johnson, accusing him of not being willing to "put his neck on the line" if he failed to meet the Hallowe’en deadline.

Repeatedly asking his opponent if he would resign if he failed to deliver Brexit by October 31, Mr Hunt challenged him to answer the question: "Will you resign if you don't deliver it, yes or no?"

Mr Johnson replied: “It's very, very important not to envisage any circumstances in which we would fail to come out of the EU on October 31.

"I don't want to hold out to the EU the prospect that they encourage my resignation by refusing to agree a deal,” he added.

Mr Hunt declared: "It is not do or die. It is Boris in No 10 that matters."

But the former London Mayor hit back, accusing his opponent of being “totally defeatist” and saying he was "not absolutely committed" to the Hallowe’en deadline.

He asked Mr Hunt how long he would delay Brexit beyond October 31. “Christmas?” he asked to laughter from the audience. He made clear that the EU would not take a "papier-mache deadline" seriously.

"If we are going to have an October 31 deadline, we must stick to it. The EU will understand we are ready and will give us the deal we need," insisted Mr Johnson.

Mr Hunt then challenged his rival on the suggestion that a no-deal Brexit was a “million to one” chance. The Secretary of State accused Mr Johnson of of "minimising the risk of a no-deal Brexit" and "peddling optimism". He insisted crashing out of the EU without a deal would “not be a walk in the park” and that it was dangerous to under-estimate the risks of a no-deal outcome as businesses would not prepare properly.

"Being Prime Minister is about telling people what they need to hear not what they want to hear," insisted Mr Hunt.

However, Mr Johnson hit back again, complaining that he had had a "bellyful of pessimism," accused his rival of “escalating the fears” of a no-deal Brexit and insisted the UK could look forward to a bright future outwith the EU.

The London MP admitted a no-deal Brexit, badly handled, could be costly but argued that if Britain prepared well it would be “vanishingly inexpensive”.

READ MORE: Boris Johnson and Jeremy Hunt debate review 

At times, Julie Etchingham, ITV’s moderator, had difficulty in controlling the two candidates as they talked over each other.

Mr Johnson, still the bookies’ favourite to lift the Conservative crown on July 23, pledged to give the country its mojo back, that he would deliver Brexit by October 31 and would take on the "semi-Marxist, wealth and job-destroying lunacy of Jeremy Corbyn and the Labour Party".

Mr Hunt insisted that as an entrepreneur said he would deliver Brexit but also “so much more”. The former Health Secretary noted: "In poll after poll I am the public's preferred choice for Prime Minister because I appeal not just to those who already vote Conservative but those we need to win.”

The former London Mayor attacked Theresa May’s Brexit deal, noting how he had resigned over it but Mr Hunt quickly pointed out that he too had voted for it in the end.

The Foreign Secretary again challenged his rival on his previous assertion there would be tariff-free trade with the EU in a no-deal situation. Mr Johnson claimed that he had never said the UK could use this power unilaterally but Mr Hunt insisted that was not what he initially said.

The Cabinet Minister quipped that getting facts wrong was alright for a newspaper column but not if Mr Johnson wanted to be Prime Minister.

On the controversial issue of suspending Parliament to force through a no-deal Brexit, Mr Hunt said: "When Parliament has been shut down against its will, we actually had a civil war. It would be a rather curious thing to do, if this is about taking back control for Parliament, to actually shut it down."

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He challenged Mr Johnson to rule it out but the former London Mayor said: "I'm not going to take anything off the table, any more than I'm going to take no-deal off the table. It's absolutely bizarre at this stage in the negotiations for the UK - yet again - to be weakening its own position."

The two contenders also clashed on tax policy. Mr Hunt said he wanted to ensure the Tories were not seen as a party of the rich and quizzed Mr Johnson on why he had announced his first tax cut would be to the better off.

The former Secretary of State insisted his agenda would be to “focus on those who are hardest pressed" and cited the expansion of the London Living Wage when he was in City Hall.

READ MORE: Boris Johnson and Jeremy Hunt debate review 

On the UK-US diplomatic spat, Mr Johnson refused to say if he would keep Sir Kim Darroch in post as UK ambassador to the US, saying: "It is vital that our civil service is not politicised by ministers leaking what they say. Whoever leaked that deserves to be eviscerated."

Mr Hunt stressed to applause: "Who chooses our ambassadors is a matter for the UK Government and the UK Prime Minister and I have made it clear if I am our next prime minister the ambassador in Washington stays because it is our decision."