The former Ukip boss said Ms May was “the wrong leader” to take Britain out of the bloc, as the EU knows she would never walk away from the negotiations, despite her mantra that “no deal is better than a bad deal”.
Mr Farage, who is regarded as one of the architects of Brexit, has been bullish in the past about Britain’s economic prospects after leaving the EU.
But he warned that Ms May was being forced into a series of damaging concessions by failing to make a show of strength to Brussels.
Mr Farage told the Today programme: “We have the got wrong leader. If we had a leader who actually believed in Brexit and was prepared to see there was a vision for the future we could make a success of it.
“We will finish up perhaps in an even worse place than we are now because we won’t be free to deregulate, we won’t be free to go out in the world and make our own deals, we won’t be controlling our own borders and we will still be accepting rules from Brussels.”
He added: “Here’s the problem – Trump walks away from things, he rather enjoys it actually. Theresa May parroted ‘no deal is better than a bad deal’, I think just to get votes in the general election and [Michel] Barnier knows the one thing the prime minister will not do under any circumstances is walk away.
“That’s why we are having to make a series of concessions, and kicking the can down the road to the extent that even if things go to plan we are not going to get any form of Brexit until at least six years after the people voted.”
It comes after a bruising couple of days for the prime minister, where rebellions over Brexit from both David Davis and Boris Johnson risked overshadowing her appearance at the G7 summit in Canada.
Ms May will gather her warring ministers at Chequers to thrash out key parts of the government’s Brexit position, where she will attempt to unite her cabinet on the details in the much-anticipated white paper.
However the away day at her Buckinghamshire residence will come after a crunch summit with EU leaders later this month.
She told EU leaders at the summit in Quebec that ”we’ll be talking about finalising withdrawal agreement but also pressing on the future relationship” during the cabinet trip.
Tensions over Brexit threatened to bubble over this week, when Ms May had to make a last-minute customs compromise with David Davis, her Brexit secretary, after he threatened to resign over her “backstop” proposals for the Irish border.
She was also forced to say she had “full confidence” in Boris Johnson, when leaked recordings emerged of the foreign secretary directly criticising her approach and warning of a “Brexit meltdown”.
The prime minister told reporters at the G7: ”People like Boris have strong views on Brexit but so do I. I want to deliver Brexit for the British people – that’s what people want. And I am getting on and doing it.”
She added: “At every stage of these negotiations we have seen people casting doubt on whether or not we will achieve what we want to achieve.”
It also comes ahead of a Commons showdown next week, where MPs are gearing up for a fraught two-day battle over the EU (Withdrawal) Bill, the government’s flagship piece of Brexit legislation.
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