Tory leadership hopeful Andrea Leadsom has taken a swipe at Theresa May, saying the next prime minister should be a supporter of the UK splitting from the EU. More Conservative MPs are speaking out in support of the energy minister's, who campaigned for Vote Leave during the Brexit referendum.

Leadsom received a boost after former Tory leader Iain Duncan Smith, who endorsed her to succeed David Cameron, said she is the "right person to lead" the UK as the country prepares to negotiate its departure from the European Union (EU).

"Having known Andrea for some considerable time, I have huge confidence in her strength, her experience, her wide range of capabilities, her calm manner and her ability to achieve objectives even against considerable odds," said Smith.

He added: "I believe that Andrea's strong family background, business experience, compassion, commitment to social justice and dedication will make her a great prime minister for the UK."

Leadsom's campaign could gain significant momentum as 30 MPs prepare to endorse the 53-year-old former banker, according to the Telegraph. The MPs were prepared to back Boris Johnson for prime minister before his campaign was usurped by Michael Gove.

Gove appears to face a tough leadership battle after he was accused of "treachery" following his decision to abandon Johnson in order to mount a bid of his own. While May remains the favourite to take over from Cameron – the home secretary has 96 of the 330 Tory MPs in parliament and the Daily Mail backing her – bookies are back Leadsom to go head-to-head with the home secretary.

Leadsom came to the fore during the EU referendum campaign, winning supporters with her argument for the UK's departure from the bloc. In an interview with the Telegraph, Leadsom said she "certainly" believes the next leader must be a Leave supporter, adding that she was "passionate about the opportunities from Brexit".

While she refrained from directly referring to May, she said: "I think it's very difficult for somebody who doesn't agree with that, who is reluctantly following the wishes of the people. I think it's quite hard for them to really see the opportunities.

"I genuinely believe that if we want to make a go of it then we need somebody who believes in it."

Theresa May sided with the Remain campaign during the referendum, saying that she wanted the UK to remain in the EU, but leave the jurisdiction of the European Court of Human Rights, which is overseen by the 47-nation Council of Europe.