Sir Vince Cable has claimed that Brexiteers get an "erotic spasm" from the thought of leaving the EU.
The insult, which will feature in his closing speech at the Lib Dem party conference is a "colourful metaphor" Sir Vince claims, intended to highlight the economic damage he says hard Brexiteers are intent on wreaking on the UK.
Sir Vince will say in the speech: "For the 'true believers' - the fundamentalists - the costs of Brexit have always been irrelevant.
"Years of economic pain justified by the erotic spasm of leaving the European Union. Economic pain felt - of course, not by them - by those least able to afford it.
- Read more: Sir Vince Cable on Brexit: 'Remain is almost certain to be a good deal better'
- Read more: Vince Cable: ‘I don’t want some self-indulgent leadership contest’
"The public don't mind what these people dream about behind closed doors - so long as their dreams don't become nightmares for the rest of us."
The veteran MP will also claim that Theresa May does not believe in Brexit.
He will add: "She is dutifully delivering a policy she doesn't really believe in - failing in negotiations, losing public support - and all to appease a dwindling group of angry people in her party who will denounce her as a traitor, whatever she comes up with.
"But, when we feel sorry for the country's Prime Minister, something is seriously wrong.
"Our sympathy can only extend so far, while she puts the interests of the country second to the whims of the extremists in her party."