Boris Johnson has pledged to get the UK "match-fit for no deal" to ensure it can leave the European Union on October 31.
The Tory leadership frontrunner said there would be "no second chances" as he stressed that Halloween was a real deadline, "not a fake one".
Mr Johnson's commitment to stick to the deadline comes after he was warned that more than 30 Tories could rebel to block a no-deal Brexit if he tried to force it through Parliament.
Mr Johnson took aim at Mr Hunt, who referred to October 31 as a "fake deadline" - before later admitting he should have described his rival's commitment to leave on that date as a "fake promise".
Mr Johnson said: "We need a change of direction. That's why we must treat October 31 as a real deadline for leaving the EU, come what may, not a fake one."
He restated his promise to protect the rights of EU expats in the UK and to put the £39bn divorce settlement in a state of "creative ambiguity" to use as leverage to secure a deal.
Discussions about the issue of the Irish border would be put into the talks on the future trading relationship under his plan.
"If our friends feel they cannot agree, then we will be match-fit for no deal."
The UK would have the "fiscal firepower" to provide cash to support business and farmers affected by a no-deal Brexit.
Mr Johnson also signalled the UK would be prepared to tear up red tape and slash taxes.
"We will be free to substantially diverge on tax and regulation," he said. "I have had enough of being told we cannot do it - that the sixth biggest economy in the world is not strong enough to run itself and go forward in the world."