Matt Hancock has endorsed Boris Johnson’s bid to become prime minister in a major boost to the leadership frontrunner’s campaign.

The health secretary, who himself withdrew from the race on Friday, said his former rival was the best candidate to “deliver Brexit and then unite the country”.

“Boris has run a disciplined campaign and is almost certainly going to be our next prime minister,” he wrote in an article for The Times.

He added: “We need to unite behind him with a strong team that can bring the party together and then bring the country together.”

Mr Hancock’s endorsement of the former foreign secretary will be seen as a particular blow to Michael Gove, who had hoped to secure his support.

Who could succeed Theresa May as Conservative leader? Show all 9 1 /9 Who could succeed Theresa May as Conservative leader? Who could succeed Theresa May as Conservative leader? Boris Johnson Former foreign secretary Boris Johnson has long been hopeful, he previously stood in the leadership contest that followed the Brexit vote and has at many times since been thought to be maneuvering himself towards the goal. He remains a darling of the party's right wing, particularly those in the ERG, and is the most popular choice among Tory voters but his leadership bid would be fiercely opposed by many MPs PA Who could succeed Theresa May as Conservative leader? Michael Gove Environment secretary Michael Gove is another member who has long wanted to be leader. He has lately been known for rousing his party in the commons, his recent speeches on the Brexit deal and Labour's no confidence motion have overshadowed the Prime Minister's. He has been loyal to the Prime Minister, partly to shed his reputation as a backstabber who abandoned Boris Johnson to stand against him in the 2016 leadership election Getty Who could succeed Theresa May as Conservative leader? Dominic Raab Former Brexit secretary Dominic Raab has emerged as a favourite to be the Brexiteer candidate in a contest to succeed to Ms May. He displayed a grip on detail in his role as Brexit secretary. When asked recently if he would like to become prime minister he replied "never say never" Getty Who could succeed Theresa May as Conservative leader? Rory Stewart International development secretary Rory Stewart is pitching himself as the sensible candidate, promising to rule out both a second referendum and a no-deal Brexit. He was only recently promoted to the cabinet, previously serving as prisons minister, where he caught headlines with a pledge to resign if he could not reduce levels of violence within a year PA Who could succeed Theresa May as Conservative leader? Esther McVey The former work and pensions secretary announced that she will be standing for the leadership when May leaves. McVey is the first to explicitly state that she intends to stand. She resigned from the cabinet in protest over May's Brexit deal AFP/Getty Who could succeed Theresa May as Conservative leader? Sajid Javid Home secretary Sajid Javid is said to have a plan in place for a leadership race. He made headlines over Christmas when he declared that people smuggling over the English channel was a "major incident" and more recently when he revoked the citizenship of ISIS bride Shamima Begum. Son of a bus driver, he wants the Conservatives to be seen as the party of social mobility PA Who could succeed Theresa May as Conservative leader? Jeremy Hunt Foreign secretary Jeremy Hunt was recently thought to be the favourite in the event of a leadership race as he could sell himself as the man to unite the party. Critics worry that his long stint as health secretary could return to haunt him at a general election. He has reportedly been holding meetings with Tory MPs over breakfast to promote his leadership PA Who could succeed Theresa May as Conservative leader? Andrea Leadsom Following the Prime Minister's second defeat over her Brexit deal, Leader of the house Andrea Leadsom hosted a dinner party at which "leadership was the only topic of conversation", The Times heard. Leadsom ran against Theresa May in the 2016 leadership election before dropping out, allowing May to become Prime Minister AFP/Getty Who could succeed Theresa May as Conservative leader? Priti Patel Former international development secretary Priti Patel is thought to be positioning herself as a contender. One MP told The Independent "she knows she's from the right of the party, the part which is going to choose the next leader, so she's reminding everyone she's there." Patel left the government late in 2017 after it emerged that she had held undisclosed meetings with Israeli officials PA

The health secretary, who campaigned to remain in the EU, last month laid into Mr Johnson for dismissing business groups’ fears about no-deal Brexit.

Mr Johnson was reported to have said “f*** business” when asked about the sector’s concerns, to which Mr Hancock responded: “To the people who say ‘f*** business’, I say f*** f*** business.”

But Mr Hancock said he had now set aside the pair’s differences and “reflected on what is needed in the national interest, and how the approaches of the candidates fit with my values”.

He wrote: “Boris is emphatic in public and in private that he wants to be a One Nation prime minister and bring the country together around an optimistic vision for the future. I will hold him to that.

“Boris and I have both used language our mothers might disapprove of in this debate. But I have been reassured, again emphatically, that a Boris administration will be pro-business, pro-enterprise, supportive of the aspirational and the international.”

Mr Hancock is the second former leadership contender to publicly endorse Mr Johnson, after Esther McVey announced her support on Saturday.

Tobias Ellwood, the defence minister, and Margot James, minister for digital and creative industries, both announced on Sunday they were backing Rory Stewart to be the next prime minister.

Ms James said Mr Stewart, who edged through to the second round of the leadership ballot with the backing of 19 MPs, had been "energetic, determined and embracing the centre ground" in the first televised debate.

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Mr Johnson came under fire from rival Jeremy Hunt for refusing to attend the Channel 4 debate on Sunday evening.

Gesturing to the empty podium installed in Mr Johnson's place, the foreign secretary asked: "Where is Boris? If his team won’t allow him out to debate with five pretty friendly colleagues, how is he going to fare with 27 EU countries? He should be here.”