Tory leadership hopefuls Boris Johnson and Jeremy Hunt have both said it’s “all to play for” as Britain waits to learn who will become the next prime minister.

Foreign Secretary Mr Hunt was in a positive mood when he arrived home from a run on Tuesday morning despite Mr Johnson remaining the clear favourite to take over from Theresa May.

With the result expected around midday, Mr Hunt said it was still “all to play for”, a comment echoed by his rival as he entered his campaign headquarters.

In a sign of unease about Mr Johnson’s expected victory, education minister Anne Milton quit the Government on Tuesday over her “grave concerns” about a no-deal Brexit, following Sir Alan Duncan ‘s departure as Foreign Office minister on Monday.

More ministers opposed to his “do or die” pledge to pull the UK out of the EU on October 31, even if there is no deal in place, could leave before Mrs May formally gives up the premiership on Wednesday afternoon.

Chancellor Philip Hammond and Justice Secretary David Gauke have given notice that they will resign rather than serve under Mr Johnson.

Mr Gauke said he believed there were “parliamentary mechanisms” that could prevent a no-deal Brexit which would “not necessarily” involve bringing down a Johnson administration.

He stressed that he would not vote against a Tory government in a motion of no confidence if it was heading towards a no-deal Brexit.

But Mr Gauke told BBC Radio 4’s Today programme: “There is a clear majority in the House of Commons that doesn’t want to leave the EU without a deal; I think that will become very clear in the autumn.”

He told the Times that newly elected Liberal Democrat leader Jo Swinson could take votes from the Tories in the event of a no-deal exit.

He said: “If we were to narrow our support to purely being those in favour of a no-deal Brexit, I think we would be significantly out of touch with a lot of people who have traditionally voted Conservative – those who live in London, the Home Counties, and various other relatively affluent parts of the country.”

Employment Minister and Johnson backer Alok Sharma called for Tory unity from ministers returning to the back benches.

Jeremy Hunt
Foreign Secretary Jeremy Hunt arrives for a cabinet meeting at 10 Downing Street (Victoria Jones/PA)

He told BBC Two’s Newsnight: “I hope what they will do is reflect on the fact that the new prime minister, if it is Boris, will actually have a mandate from the parliamentary party and from the membership.

“What we will do if we have disunity in the party is risk a Corbyn government.”

Arch Brexiteer Nigel Evans, a senior member of the 1922 Committee of backbench Tory MPs, predicted Mr Johnson’s arrival in Downing Street, telling the BBC: “He will be going in there … with at least half a dozen knives already in his back.”

Boris Johnson
Boris Johnson leaves his office in Westminster (Yui Mok/PA)

Mrs May will tender her resignation to the Queen after taking Prime Minister’s Questions in the Commons on Wednesday afternoon for the final time, with the new Tory leader set to enter Number 10 soon afterwards.

The new prime minister will have to govern with a Tory-DUP majority of just two, after Dover MP Charlie Elphicke had the Conservative whip suspended when he was charged with sexually assaulting two women.

The Government majority could be further reduced next week if the Tories lose the Brecon and Radnorshire by-election.