While some Conservatives openly back former foreign secretary, others say they may quit if he becomes PM

Boris Johnson’s leadership campaign was gathering steam on Thursday, amid deep concern among centrist Conservatives that a Brexit hardliner is on the brink of becoming prime minister.

The former foreign secretary gained two significant endorsements – Johnny Mercer, who had been considered a leadership hopeful himself, and Gavin Williamson, the former defence secretary – with more poised to make themselves known in the coming days.

Johnson has the public backing of at least 10 MPs including Jacob Rees-Mogg, the chair of the European Research Group, Zac Goldsmith, the former London mayoral candidate, and John Whittingdale, the former culture secretary.

Williamson, a former chief whip, told his local paper, the Express and Star: “He’s the one who can deliver change for both the Conservative party and the country.

“I will be enthusiastically backing him and very much hope I can play a small role in making sure that his name is the one that the party chooses as leader. The bottom line is that the only person who can deliver Brexit and defeat Labour is Boris Johnson.”

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Johnson, an architect of the Vote Leave campaign, is the firm favourite to take over as Conservative leader if he wins enough support among MPs to make it on to the final list of two candidates to be put to the party membership. To guarantee a place on the final ballot, candidates need at least 105 Conservative MPs behind them.

A “Stop Boris” movement has been under way among some centrist anti-Brexit MPs, from members of the cabinet to backbenchers, but there is a growing sense among them that it may be impossible to keep him off the ballot.

“My worry is that colleagues will think he has the best chance of saving their seat at the next election – wrongly, in my view,” said one anti-Johnson MP.

Another said there was growing concern among One Nation Tories that Johnson was likely to be leader, comparing their position to that of Labour MPs on the right of the party under Jeremy Corbyn’s leadership.

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Johnson’s chances and those of other Brexiters – Dominic Raab, Penny Mordaunt and Andrea Leadsom – are also likely to be boosted by the fact a Brexit deal remains unresolved, allowing them to resurrect arguments for a renegotiation and, if that cannot be achieved, a so-called “managed no-deal”.

One supporter of a pro-Brexit leadership candidate said most of the cabinet hopefuls – Sajid Javid, Jeremy Hunt, Matt Hancock and Michael Gove – were “in a real bind” because they had backed Theresa May’s doomed withdrawal agreement up until the very last moment and would have to ditch their support for it in any leadership contest.

“These cabinet ministers are all going to have to come and say they will have one last shot at renegotiation and then they are open to no deal after all. But they have all been going round saying how terrible no deal is so it is going to look completely disingenuous,” he said.

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“Anyone who doesn’t put no deal back on the table is going to have no chance with the members. But they have backed the PM’s deal all the way through and they can’t just blame her for it now without it looking really bad.”

With Johnson gaining momentum, some moderate Conservatives are even considering their place in the party. One told the Guardian that some MPs are thinking of leaving if a hardline Brexit supporter is picked as the prime minister, meaning there could be no majority to govern even with the support of the Democratic Unionist party.

“I wish the Conservative party’s problems were as easy as changing the leader,” said one centrist Tory MP. “The Brexit party is eating our core vote … after three years of not delivering on Brexit it’s hard to credibly beat them now.

Quick guide Tory leadership contenders Show Hide Jeremy Hunt His style is notably technocratic, with few rhetorical flourishes and an emphasis on his consensual approach and long record as a minister, notably during more than five years as health secretary, a traditional graveyard of ministerial careers. Hunt’s attempts to talk up a backstory as an 'underestimated' entrepreneur can fall flat given he is also the son of an admiral and was head boy at Charterhouse. Overall, Hunt’s approach can seem uninspiring and hard to pin down in terms of core beliefs, hence the 'Theresa in trousers' nickname among some Tory MPs – one that is more catchy than accurate (since May herself often wears trousers). In the final round of MP voting Hunt edged out Michael Gove, 77 votes to 75. Boris Johnson Johnson’s progress to Downing Street appeared unstoppable even before an overwhelming victory in the first round of voting among MPs. Most of his colleagues believe it is now all but inevitable that he will be Britain’s next prime minister. His well-disciplined campaign team will continue with their strategy of subjecting him to minimal media exposure, though once the field is narrowed down to two, the final pair will appear in more than a dozen head-to-head hustings for Tory members. The team’s main aim is simply to keep heads down and avoid Johnson creating headlines for the wrong reasons. It may not have worked. Johnson came first in the final round of MP voting with 160 votes.



“I think the party has got to think very carefully about thinking all its problems can be solved by out-Brexiting the Brexit party, which comes at a price of alienating a huge swath of Britain that doesn’t want hard Brexit and is almost certainly the majority.”

Dominic Grieve, a pro-EU Conservative MP, hinted he could quit the party in the event of a no-deal Brexit on Wednesday, telling ITV’s Robert Peston: “I’ve always said that I think taking the UK out of the EU without a deal would be catastrophic and I would do everything in my power to prevent it.

“Because the question is ‘what do I have to do to stop it?’ I would have to do everything I can.”