Brexit negotiations must be put on hold and Theresa May must quit, Tim Farron has said.
The Liberal Democrat leader said talks about leaving the European Union, which are due to start in 11 days, should be delayed while the new government reviews its priorities and sets them out to the public.
Mr Farron, re-elected as Westmorland MP by the narrowest of margins last night, insisted there would be no deal to prop up a Conservative government, using Mrs May's own words against her by insisting "no deal is better than a bad deal".
"Like David Cameron before her, our Conservative Prime Minister rolled the dice with the future of our country out of sheer arrogance and vanity," he added.
Mr Farron said EU exit talks were "about to get very real" and warned the "consequences will be felt by every single person in this country".
The dire result for the Conservatives showed Mrs May's "extreme version" of Brexit had been rejected by the British people, he said.
"It is simply inconceivable that the Prime Minister can begin the Brexit negotiations in just two weeks' time.
"She should consider her future - and then, for once, she should consider the future of our country," he said.
"The negotiations should be put on hold until the Government has reassessed its priorities and set them out to the British public.
"The British people have a right to expect that our Prime Minister will explain to them what it is that she seeks to achieve."
The Lib Dem case for a referendum on the final Brexit deal "will only get stronger" as the talks continue, he claimed.
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