Theresa May promised that she wouldn’t call an election in 2017; that her Brexit policy would be based on “a comprehensive system of mutual recognition”; that migration would be controlled during transition; that transition wouldn’t be extended; that she would oppose new regulatory barriers in the Irish sea; that it would be “unacceptable” to hold European elections…and over 100 times that we would leave the EU on March 29. She then said that she was not prepared to delay Brexit later than the end of June.

It was clear after the second “meaningful vote”, if not before, that MPs wouldn’t let the Withdrawal Agreement pass. The Prime Minister could have resigned at that point – acknowledging that the Commons would not now let Britain leave the EU at the end of March, and that the only honourable course left to her was to quit. Instead, she clung on. The Conservatives’ poll ratings began to fold during the next few days. They have not reached above 40 per cent since March 16, the end of the week that saw the announcement of a vote on extension.

The European elections saw the Tory share of the vote crumble to nine per cent. Only four blue MEPs were returned. The Party came third in the Peterborough by-election. Its last five opinion poll scores were 26, 18, 17, 19 and 28 per cent.

Had the Conservatives a working majority in the Commons, they would perhaps have time to turn all this round. But they currently hold only 313 seats – and May’s EU policy has alienated the Party’s confidence and supply partner, the DUP. None of the new Brexit policies advanced by the Tory leadership candidates are likely to fare any better in the House than May’s did – whether they seek to amend her deal, scrap it and start again, go for No Deal outright or aim for a second referendum. Extension – Michael Gove’s policy in extremis – only puts off the evil day.

The Labour Party, the Tory second referendum supporters and the “Spartans” can defeat anything based on the Withdrawal Agreement. The Speaker can bend procedure to allow emergency legislation to block No Deal. A second referendum – as backed by Sam Gyimah alone among the contenders – would require a Bill. And there is no majority for that either. There is no evidence that the Queen would, as her flawlessly judged reign draws nearer her end, mar it by agreeing to an emergency prorogation.

All of which means that the Conservatives are, almost certainly, not choosing a Prime Minister for the long haul. May’s replacement will probably find himself contesting a general election within a year. He could face a snap vote of no confidence as early as the end of this month (in the event of there being no membership stage to the contest).

It follows that the Party faces the possibility of an election with four parties gaining about a quarter of the vote each. At which point, the logic of first past the post turns against it. There is the possibility of a Canada-type wipeout of the Tories.

Even a small swing to Labour would return a Marxist-led government for the first time in our history. So Conservative MPs should vote this week for the candidate most likely to save Tory seats and win an election. Who best fits the bill?

A problem right at the start is that voters are not familiar with most of the contenders. Never over-estimate the electorate’s interest in who’s who within the Westminster Village. So it is, for example, that nearly half of voters have never heard of Dominic Raab, according to YouGov. The danger for him and others in his position, were he to become Prime Minister, is that they would have no time to cut through. This committed Brexiteer, who is under sustained assault from the Tory Left and the Left generally, would risk being written off as a “May in trousers”.

Opinion polls are ambiguous, sometimes contradictory, occasionally polluted and, in a sense, premature: after all, the leadership election has not formally begun yet. Perhaps Raab or one of the less well-known candidates would be able to turn voters round. Maybe Jeremy Hunt or Michael Gove could rise on the stepping stones of their dubious ratings to higher things. But as matters stand, only two candidates look like winners with the public: Sajid Javid and Boris Johnson.

In the words of YouGov’s Marcus Roberts on this site last week, “voters…consider Johnson the most electable Conservative candidate (37 per cent) with Javid trailing a full twenty points behind (17 per cent). Johnson is the most popular Tory politician in its table, and Javid tenth – the next most popular of the contenders.

There is a case for Javid. His negative rating, at 28 per cent on YouGov’s findings, is relatively low. We are sceptical of the claim that “back story” makes much difference to party leaders, but it looks as though the Home Secretary’s does have some cut-through. None the less, almost three-quarters of the public have apparently never heard of him. Javid has spent much of his career reacting to events: the Grenfell horror, the problem of Shamima Begum, knife crime. Does he have the capacity to shape them – to make the political weather?

Johnson undoubtedly does. True, he brings storms as well as sunshine. His commitment to leave in the EU referendum has pushed up his negative ratings. And he remains, as Dominic Lawson has put it, “epically unreliable”. Johnson’s essence is that he seems to see himself as an Odyssean figure, not to be bound by the irksome restraints of conventional morality. He is best placed of the candidates to win back votes lost to the Brexit Party – an emergency requirement – but one can never be sure what he would do afterwards.

Left to himself, he wanders off into scrapes, puns and odium. Minded and directed, he is more than capable of real achievement. Stuart Reid at the Spectator; Simon Milton and Eddie Lister at City Hall; Dominic Cummings at Vote Leave: all got the best out of him. He was a popular and capable Mayor of London, winning twice in what is naturally a Labour city. Malice is notably absent from his list of faults. Perhaps that’s why so many voters take to him. He is the sole candidate in this contest to have the X factor.

Jeremy Hunt would provide surer government for the long-term that this election doesn’t offer. In more turbulent ones for the economy, Raab would be our man for leading a national response to crisis. Javid has his appeal. Matt Hancock seems to us really to be running for Chancellor. Rory Stewart has emerged from this contest as the non-Leavers’ favourite Tory. That might not necessarily translate into votes in an election.

Touching wood – and on the understanding that we will be cheerfully denouncing him within a week of his election – ConservativeHome is for Johnson, if he gets the band back together, and brings the old Vote Leave team into Downing Street. They helped to make Brexit, after all; now they should deliver it. If the Tories want the leader best placed to see off Jeremy Corbyn and Nigel Farage, Johnson is the man.

If he can do so, he will need all the help he can get afterwards. If Hunt is the runner-up to Johnson in this contest, there is a very strong case for making him Deputy Prime Minister, and letting him run much of the government. A test for Johnson is what he makes of his brilliant, haunted and creative rival, Gove. He too would have the capacity to range across government, as a kind of souped-up David Lidington.

But we are getting ahead of ourselves. What a Johnson-led, infrastructure-friendly, NHS-friendly, One Nation-flavoured govenment would and should be like is for another day. His fans like to paint him less as a Odyssean figure than a Churchillian one: Sir Winston Johnson, risen at this darkest hour to deliver the referendum result, save his party and revive his country, with bounce and brio.

It may be better in his case to look to fiction than history. In The Dark Knight, one of the characters is described as “not the hero we deserved, but the hero we needed”. Perhaps Johnson is not the Prime Minister that the British people deserve. Even some of those who will vote for him on Thursday would balk at that claim. But he is the Prime Minister that we need right now. On a wing and a prayer, ConservativeHome endorses him.