Boris Johnson has attacked UK prime minister Theresa's May's Brexit plan, saying she had "wrapped a suicide vest" around the British constitution and "handed the detonator" to Brussels.
In the Mail on Sunday, the former foreign secretary said the Chequers deal was "feeble" and "pathetic".
He has been strongly criticised by some members of his own party - one minister said it marked a "disgusting moment" in politics.
And Home Secretary Sajid Javid called for "measured language" to be used.
Writing in the same paper, current Foreign Secretary Jeremy Hunt called for people to rally behind Mrs May, backing her to hold the line "in the face of intense pressure".
The UK is leaving the EU on 29 March 2019, and the government's plan - agreed at Chequers in July - has sparked criticism from Brexiteer Tories as well as the EU.
In his article, Mr Johnson accused the EU of "bullying" the UK - but questioned why the response had been "so utterly feeble".
He said that rather than getting a "generous free trade deal", Britain was saying, "yes sir, no sir, three bags full sir", to Brussels.
"At every stage of the talks so far, Brussels gets what Brussels wants," wrote Mr Johnson.
"It is a humiliation. We look like a seven-stone weakling being comically bent out of shape by a 500lb gorilla."
Irish border deal
He said the reason for the UK's response was the "insanity of the so-called backstop" - the commitment by the UK and the EU to come up with a solution to avoid a hard border on the island of Ireland between Northern Ireland and the Irish Republic.
However, his call to scrap the proposed backstop has been heavily criticised by Sinn Féin and the Irish nationalist Social Democratic and Labour Party.
Sinn Féin said Mr Johnson's comments were "foolish and dangerous", while the SDLP said he had "absolutely no regard for people on this island".
It is Mr Johnson's second attack on the prime minister's Brexit strategy inside a week, as last Monday he said the Chequers deal "means disaster" for Britain - Downing Street responded to that attack by saying he had offered "no new ideas".
While Mr Javid voiced measured criticism of Mr Johnson, other Tories reacted more angrily to his remarks.
Foreign Office Minister Sir Alan Duncan criticised his former boss, saying the article was "one of the most disgusting moments in modern British politics."
If this latest broadside was not the end of Mr Johnson's political career, "I will make sure it is later", he said.
Another Foreign Office minister, Alistair Burt, tweeted: "I'm stunned at the nature of this attack. There is no justification for such an outrageous, inappropriate and hurtful analogy.
"If we don't stop this extraordinary use of language over Brexit, our country might never heal. Again, I say, enough."
But backbench Tory MP Nadine Dorries defended Mr Johnson in the face of what she was "vitriol", saying his critics were "terrified of his popular appeal".
And Tory Brexiteer Andrew Bridgen said the way Mr Johnson "says it how he sees it and speaks truth unto power" was "something that endears him to a huge swathe of the British public".
Elsewhere the National Police Chiefs' Council said there was no intelligence to suggest there would be an increase in crime or disorder if the UK and the EU cannot agree a deal.
NPCC operations lead Chief Constable Charlie Hall was responding to a Sunday Times report of a leaked document about police contingency plans for a no-deal Brexit.
According to the paper, the document warned that concerns around medical supplies could "feed civil disorder", and that potential goods shortages raised concerns of "widespread protest which could then escalate into disorder".
It also warned that the "necessity to call on military assistance is a real possibility" in the weeks after UK's departure from the EU.