Nigel Farage has said Theresa May is a "weather cock and not a signpost", and that his confidence in the Prime Minister to deliver on Brexit is falling by the day.
The former Ukip leader was in Clacton-on-Sea as he joined the party's candidate for Clacton Paul Oakley for a morning of campaigning - his first of the General Election.
Theresa May: I will make Brexit work for Yorkshire
Mr Farage's visit came as the news broke that Tory candidate Craig Mackinlay, who beat him to the South Thanet seat two years ago, has been charged over allegations relating to his 2015 election expenses.
Mr Farage described Margaret Thatcher as a signpost who knew the direction to take, but likened the current Prime Minister to someone who "blows around in the wind".
"She is a weather cock and not a signpost," he said.
"I, for the life of me, have no idea what she believes in, Brexit being the best example."
Mr Farage said it is "tough" to believe Mrs May and said his confidence in her to deliver has "fallen by the day".
He added that she "U-turns on everything".
"I have very little confidence in her, her record of delivery as the longest serving Home Secretary since the nineteenth century was abysmal," Mr Farage said.
"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."
Picture-seeking passers-by regularly stopped the MEP as he made his way past amusement arcades and on to Clacton Pier on Friday.
Once he arrived, Mr Farage was followed around the town by a group of Ukip placard-carrying supporters, and he regularly stopped to speak to voters and answer their questions.