Sajid Javid warned that the contest for the next prime minister must not “look like a debate at the Oxford Union” as he battled to secure the support needed to remain in the race.

The Home Secretary, the only candidate left in the race not to have gone to Oxford University, said it would not be “healthy” for the party if all the candidates left in the contest had similar backgrounds.

Mr Javid and International Development Secretary Rory Stewart are fighting to secure the 33 votes needed to stay in the race.

Tory leadership race: Sajid Javid
(PA Graphics)

Allies of the Home Secretary, who won 23 votes in the first round, acknowledged it would be “close” and claimed Mr Stewart’s camp were trying to win over his supporters.

Mr Stewart secured just 19 votes last week but his campaign has gathered momentum and he hopes to get the 33 required.

“I think we’re there, but it’s tight,” a campaign source said.

Mr Javid, the state-school educated son of a Pakistani bus driver, has a background which is in stark contrast to rivals including Old Etonians Boris Johnson and Mr Stewart.

He told BBC Radio 4’s Today programme: “If we end up in a situation where the final two, three, four even, are people from similar backgrounds with similar life experiences, it will look like a debate at the Oxford Union and I just don’t think that’s healthy for the Tory Party.”

The Home Secretary joked that his style was “less Homer’s Iliad and more Homer Simpson”.

In a sign that the contest is becoming more personal, a former aide to Mr Javid claimed Mr Stewart’s supporters were targeting the Home Secretary’s backers “urging them to vote for Rory so we can offer ‘something different’ in final two”.

On Twitter, Mr Javid’s ex-special adviser Nick King added: “Saj’s dad was an immigrant. Saj went to his local comp and an FE College. Rory went to Eton and Balliol just like Boris.”

PA Graphics
(PA Graphics)

Mr Stewart is trying to position himself as the “change” candidate who can defeat Mr Johnson in the July run-off.

He told BBC Radio 4’s Today programme that he has “no problem” being the “stop Boris” candidate, and that he would “love” to go against Mr Johnson in the final two.

“I have no problem with that, and I would love to go against him in the final two in order to give members the chance to choose whether they want Boris’s Brexit or mine.”

Sources in former Brexit secretary Dominic Raab’s campaign were “quietly confident” he would pass the threshold, having secured 27 votes in the first round.

In a new campaign video Mr Raab said his love of karate and boxing had “been pretty good in terms of preparing me for other big moments”.

He highlighted the importance of education, saying “everyone should have the opportunity to go as far as their talents can take them”.

The second round of voting comes ahead of a live TV debate that will feature the front-runner and former foreign secretary, Mr Johnson, who picked up 114 votes last week and has gained support since.

Mr Johnson received the endorsement of former leadership contender Andrea Leadsom on Tuesday morning, who said he was the “best placed to get us out of the EU at the end of October” and an “election winner”.

Tory leadership contest timetable (PA Graphics)

The former Commons leader told LBC: “I’m going to be backing Boris Johnson for the next prime minister. Essentially, there are two key reasons.

“One is I think he is the best placed to get us out of the EU at the end of October, so his view and mine is very closely aligned there, and secondly, I do believe he is an election winner.”

Tory leadership race
Andrea Leadsom said Boris Johnson was the “best placed to get us out of the EU at the end of October” (Stefan Rousseau/PA)

Meanwhile, the Environment Secretary Michael Gove, who came third in the first ballot with 37 votes, said the final two candidates should “believe in Brexit” and be able to deliver it and unite the Tory party.

PA Graphic
(PA Graphics)

“It would be a mistake to put forward two candidates to the final round who will polarise our party,” he wrote in The Times.