Nigel Farage's faith in Theresa May delivering on Brexit is dwindling by the day, he claims.
The former Ukip leader suggested the Prime Minister's position on Brexit is unclear and accused her of u-turning "on everything".
Speaking during a day of campaigning in Clacton-on-Sea, Essex, the Eurosceptic compared Mrs May to a "weathercock" and "not a signpost".
Mr Farage said it was "tough" to still believe she would deliver on the right Brexit deal.
Mr Farage's visit to Essex came on the same day that Conservative candidate Craig Mackinlay was charged over an alleged election expenses scandal.
Mr Mackinlay beat opponent Mr Farage to the South Thanet seat in 2015.
Speaking of the Prime Minister, the former Ukip leader likened her to someone who "blows around in the wind".
"She is a weathercock and not a signpost," he said.
"I, for the life of me, have no idea what she believes in, Brexit being the best example."
He said Mrs May "U-turns on everything", adding: "I have very little confidence in her, her record of delivery as the longest serving Home Secretary since the nineteenth century was abysmal.
"She clearly can't stick to a course because she does just get blown off course.
"I think she may well have been the Tories' big asset on April 18, but she is now their biggest liability."