Boris wanting to be prime minister is not newsworthy. In fact, unsatisfied with the humble position of Captain of the School, Alexander Boris de Pfeffel Johnson (KS) has made his ambition to take up residence in Number 10 perfectly clear since Eton days. After dramatically backing Vote Leave and closing the BBC’s Brexit debate to rapturous applause in a stirring call for national independence, many expected to see his ambition realised within months of David Cameron stepping down. Indeed, love him or loathe him, there seemed to be an inevitability about the maverick former London Mayor’s resistible rise.

But it was not to be. After a factioneering failure when Boris forgot to send the right text message at the right time to Andrea Leadsom to secure her support, Michael Gove had a meltdown and withdrew from his so-called dream ticket alliance with Johnson. Without the support of these other two key Brexiteers, Johnson knew he didn’t have the support he needed from the party’s MPs. With many of his colleagues alarmed about his competence and others furious at his disloyalty to the Prime Minister, there is no way that enough parliamentary backing could be guaranteed.

In the first of two well-timed sideways moves on his journey towards the crown, Johnson shocked the public and the media by withdrawing from the race. The decision was, for him, a good one. Any prime minister would inevitably be left tarnished, if not utterly discredited, by the Brexit maelstrom. By allowing someone else – as it turned out, the unfortunate Theresa May – to offer themselves as a lamb to the Brexit slaughter, Johnson could 

The second key decision was stepping down from the Cabinet this year. Boris had been made Foreign Secretary, most probably because it’s a job in which he could be controlled by civil servants and bound by diplomatic convention. By resigning over the Prime Minister’s compromise Chequers proposal, Johnson freed himself from the rules of ministerial collective responsibility, allowing him the freedom to attack May and act as the defender of the referendum result (and hence democracy) against an alleged government sell-out. In short, he could play King-over-the-water to the Brexit faithful.

Which is exactly what he has done. Last week Boris launched another attack on May’s Brexit strategy, labelling it a “humiliation” and calling for a Canada-style free trade deal instead. In a BBC interview he refused to rule out a leadership bid, talking a little incoherently about how May will stay “for as long as she deems necessary”, while defending the Leave vote and his role as a guardian of it. He acquitted himself with aplomb in the face of hostile questioning from ITV’s Robert Peston, too. The timing is significant; as this shambolic government limps through its 2018 Birmingham conference, Boris is setting himself up as an alternative to the hapless and struggling May.

Can Boris become PM? Under Conservative party rules the MPs vote until, Highlander-style, only two remain, before the choice goes to the grassroots. The latest Conservative Home poll of members puts Johnson on 30% support from Tory members in a clear double-digit lead over runner-up Jajid Javid, the Home Secretary, suggesting the he would win a final vote easily. But the Stop Boris movement is strong, and it’s not out of the question that the parliamentary party could conspire successfully to get two non-Boris candidates to the final round, thus blocking him out. Given how far he has alienated his colleagues, getting to this stage is Boris’s biggest leadership hurdle.

In any case, Boris can’t simply declare and run for the leadership. One of a number of things would need to happen first.

There could be a no confidence vote in the Prime Minister. For this to happen Graham Brady, the Chairman of the backbench 1922 committee, must receive 48 letters calling for her to go. The most organised anti-Brexit faction in the party is the European Research Group (ERG), but in their meeting last month it seemed that no more than five were keen to begin her removal. The scenario in which a move is most likely would be if May’s final deal is voted down by Parliament, in which case a leadership race could be triggered. Boris’s task is then to get to the final round.

Alternatively, there could be a snap general election. This could happen now if two thirds of MPs vote for it (under the Fixed Terms Parliament Act), which is unlikely given the seriousness of the repercussions should the government fall before the Brexit negotiations are complete. Or, if the vote on the final Brexit deal is lost in the Commons, there could be either a Tory leadership race if the PM stands down, or a general election aiming to secure the kind of majority that could get an exit deal through. Either could see Boris emerge as leader and potentially prime minister.

Most alarmingly for Johnson,  the most recent BMG poll for HuffPost UK now shows Labour on a 5-point lead over the Tories, and indicates that Corbyn is preferred by the public as leader over Johnson by 29% to 20%. If Boris had to lead the Conservatives into a vote, it’s not at all certain that he would win. The polling suggests that even if the Tories regain a poll lead over Labour, Johnson’s public image as a leader could still hamstring the party – the mop-haired Churchill enthusiast’s previous popularity notwithstanding.

A final possibility is that there’s an election, Labour win, and Boris emerges as Opposition leader. After five years of disastrous economic policy under Corbyn, he leads a Conservative resurgence. But perhaps by then he’ll have given up. Brexit was Johnson’s great opportunity to fulfil his dream, but the pathway ahead is a jungle from which only the savviest political operator can emerge well. He might have had a serious shot at unseating May after the 2017 election debacle, but that was an opportunity not taken. Does he have the wherewithal to go the distance in pursuit of a prize that may never be his? Boris may have missed his chance already.