Liberal Democrat leader Sir Vince Cable is accusing ministers of behaving like dictators over Brexit.
Sir Vince is using his first keynote address to the Lib Dem conference as leader to call for "political adults" in Tory and Labour ranks to join forces with him and try and reverse withdrawal from the EU.
He is challenging Foreign Secretary Boris Johnson and other Brexiteers to defend any deal hammered out with Brussels in a new referendum.
The Lib Dem leader is saying: "What are they afraid of? Are they afraid that the claims of £350 million a week for the NHS won't wash any more?
"That claim has rightly been dismissed by the UK Statistics Authority. No wonder Boris and the Brexiteers are so afraid of the people, and the facts.
"They now believe in the slogan of dictators everywhere: 'one person, one vote, once'.
"We believe the public have a right to change their mind. At the end of these tortuous divorce negotiations, the British public must be given a vote on the outcome."
Sir Vince is calling for a cross-party effort against a hard Brexit.
He is saying: "What the country now desperately needs is some political adults. There are sensible grown-ups in the Conservative Party, and the Labour Party and the Greens.
"We have to put aside tribal differences and work alongside like-minded people to keep the single market and customs union, essential for trade and jobs."
Sir Vince is saying that the sharp drop in the pound since the referendum is a taste of things to come.
"Foreign exchange dealers are not point scoring politicians. Their cold, hard, unsentimental judgement has been, quite simply, that Brexit Britain will be poorer and weaker after Brexit than if we had decided to stay in Europe."
The Lib Dem leader is using the address to demand that Prime Minister Theresa May guarantees the rights of EU nationals in the UK.
"Using them as bargaining chips is not merely morally wrong but utterly counter-productive. Put the lives of four million people first, not the posturing internal politics of the Conservative Party. No ifs, no buts."
Sir Vince is accusing Labour leader Jeremy Corbyn of trying to face both ways on Brexit.
The Lib Dem leader is saying: "He would do better to get off the fence and refurbish his revolutionary credentials. Jeremy - join us in the Anti-Brexit People's Liberation Front."
Sir Vince is comparing Cabinet differences on Brexit to a public school pillow fight.
"A disaster looms - Brexit. The product of a fraudulent and frivolous campaign led by two groups of silly public school boys reliving their dormitory pillow fights.
"And now, thanks to Boris Johnson, they have degenerated into a full-scale school riot with the head teacher hiding, barricaded in her office.
"Brexit was described by the Brexit Secretary himself as an operation of such technical complexity that it makes the moon landing look simple.
"It is a pity that the Brexit landing is being managed by people who would struggle to get their heads around a toddler's Lego set. They live in a world of infantile fairy tales."