Mr Johnson has branded the Prime Minister's Chequers plan "deranged" and compared it to putting a "suicide vest" on the British constitution.
Mr Boris Johnson is more known for burning bridges than for building bridges!
"It's always unsafe getting into hypotheticals about what people may or may not say in the future, even if it's just later on today", he said.
"He is absolutely right about the threat that Chequers poses to our democracy, our country and ultimately the fortunes of the Conservative Party if we stick with it", Andrew Bridgen, a Conservative lawmaker, said. This is not what we voted for. This is an outrage. "It's not taking back control".
"I think the Chequer's plan is completely unacceptable for a country like Britain which has been a sovereign country for a thousand years, we've written our own rules, we can not have the worst of both world's - that is to say, to have people's rules without any chance of writing them".
But while Johnson may be holding his fire on the leadership for now, he gave both barrels to May's Brexit plan and set out his vision for the Conservative Party - one that returned to its traditional values of low taxes and a strong police.
While the main hall of the Conference has been at best half-full through for most of the time, there wasn't a free seat at Boris's so-called fringe meeting.
Setting out her plans for a festival in post-Brexit Britain, she said: "We want to showcase what makes our country great today.
What it says is, if a conflict situation, armed conflict obviously, appears to be arising, the Northern Ireland people themselves will have a referendum", he said.
Britain is due to leave the European Union on March 29, 2019, but the terms of the departure remain unclear.More news: President Trump and FEMA to test cell phone alert system on Wednesday
Mr Johnson has argued for months that the PM has lost sight of these goals and set out a plan that leaves Britain too close to Brussels.
"It occurs to me that the authors of the Chequers proposal risk prosecution under the 14th century statute of praemunire, which says that no foreign court or government shall have jurisdiction in this country", he told Tory activists.
The Chequers blueprint, agreed by Mrs May's top team after marathon talks in July, would see Britain adopt a common rulebook for trade in goods with the EU.
"Boris always puts on a good show, but what matters to people is what we are delivering for them on the things that affect their day to day lives", she told Sky News.
"Because if we get it wrong we will be punished. So why we can think that Ireland's going to be such a disaster, I don't know.", he continued.
"This government will then be remembered for having done something courageous and right and remarkable and in accordance with the wishes of the people".
Responding to Johnson's claims she doesn't believe in Brexit, Mrs May suggested her Chequers plan is the only option that will "get a really good" deal with the EU.
And he urged Tory delegates to persuade the Prime Minister to return to the hard Brexit blueprint she first set out in her Lancaster House speech, when she said she would take the United Kingdom out of the customs union, single market and jurisdiction of the European Court of Justice. But undoubtedly the biggest reaction came from his attack on the Prime Minister's Brexit proposals; cheers and enthusiastic clapping as he urged the party to "chuck Chequers".
The comments "brought immediate comparisons on social media to the "lock her up" calls from Donald Trump's supporters about former U.S. presidential candidate Hilary Clinton", says Business Insider.