Michael Gove should be installed as the new Tory leader because Theresa May has shown that she cannot “carry Brexit through”, a major party donor has publicly warned.

In a stark sign of the frustration among prominent Brexit supporters over the government’s handling of negotiations with the EU, Crispin Odey, a hedge fund manager who backed the Leave campaign, said he believed the environment secretary had the skills to make a success of Britain’s exit and appeal to voters.

Odey, whose most recent donation to the Conservative party was a £50,000 gift before last year’s general election, said the government needed to be far bolder in its attitude to Brussels. It should be learning from the new Italian populist coalition government, which has plans that would defy EU rules on debt, he said, suggesting that Britain should start breaching EU rules by pursuing policies such as signing trade deals. He also backed a change in leadership.

“We’ve got to have that self-confidence to make breaches,” he told the Observer. “There’s no point in voting for freedom if you don’t know what to do when you’re free. What is true is that you have a whole lot of people who didn’t want this to happen who are in charge of it happening.

“I would go to Gove. He’s the only minister who is still being a minister. Michael has got lots of attributes that make him a non-traditional Tory. He is very aware that he has to appeal not just to the wealthy, but also more broadly. I don’t think May can carry Brexit through any more.”

He added: “Italy has confronted the EU – they’ve said they will go ahead and be in breach of its rules.

“We should say, ‘we’ve got to have life after this, so we’re creating that life. We are creating trade agreements which are in breach of everything, because we won’t be in breach by the time you come to take us to court’. That’s how Elizabeth I would have been leading with this.”

Facebook Twitter Pinterest ‘Theresa May is not good at hitting a moving ball,’ says Odey. Photograph: Oli Scarff/AFP/Getty Images

His backing for Gove risks reigniting the Tory debate about May’s leadership, with some Brexiters worried that Britain could end up being locked into a customs union with the EU that would prevent it pursuing an independent trade policy. In reality, few Tory MPs want an unpredictable leadership election which could further destabilise the party. However, a challenge to May’s leadership could emerge should pro-Brexit MPs conclude there is a better alternative.

Gove was one of the figureheads of the successful Vote Leave campaign. His botched attempt to succeed David Cameron in 2016 saw him widely condemned by Tory MPs for betraying Boris Johnson, whose leadership bid he had been supporting. He was then sacked from the frontbench by May. However, he has been enjoying something of a renaissance since returning to the cabinet as environment secretary last year. “No other politician could have made such an impact in that job,” said an ally.

A source close to Gove said the environment secretary was “fully supportive of the prime minister and will continue to be so”. He added: “He believes it’s vital we get behind our prime minister to deliver the Brexit 17.4 million people voted for.”

Odey, who has also donated to Ukip in the past, said he believed that May was a gifted technocrat, but questioned her handling of Brexit. “The European Union are not good at hitting a moving ball,” he said. “The problem is, Theresa May is not good at hitting a moving ball, either.

“As someone said about May, she should have joined the civil service, rather than becoming a politician. She is perfect for that, but she can’t make a decision. So there is no leadership.

“We should be reaching out to Italy. We should be saying that we have so many of the same problems.”