Who is worse, conciliatory Boris Johnson or his petulant doppelgänger?

Boris Johnson ran as two candidates to win the Tory leadership, adjusting his persona to suit different audiences. For wary Conservative MPs who doubted his professionalism, he played the moderate conciliator and Brexit pragmatist. To the activist base he preached Eurosceptic fire and brimstone, unafraid to wreak havoc in the cause of emancipation from Brussels bondage.

True to that model, Johnson now serves as twin prime ministers. One promises ecumenical government and speaks of “healing a divided nation.” The other sought illegally to prorogue parliament when it would not yield to his will, and colludes in the sinister stigmatisation of pro-European MPs as collaborators with a foreign power.

Practical Johnson made significant compromises in Brussels to secure a Brexit deal and hints at further concessions to opposition MPs if they will help secure its passage through the Commons. But after that prime minister lost a vote on the legislative timetable, his petulant doppelganger re-appeared, threatening to boycott parliament if it will not rubber stamp his deal and then immediately dissolve itself for a general election.

In Westminster, these mood swings are attributed to rival factions within Downing Street. The bellicosity is said to come from Dominic Cummings, director of the 2016 Vote Leave campaign, now Johnson's most powerful consigliere. Counsels of diplomacy are thought to be provided by veteran staffers carried over from Johnson's time as Mayor of London, such as Eddie Lister, his former chief of staff in City Hall. Political commentators find it hard to resist that kind of Kremlinology, but often division and dysfunction in an administration are better understood as the expression of competing traits in the character of the leader, or consequences of a nasty political dilemma.

There is an irreducible tension between the need to govern and the need to campaign. Johnson has wanted to be prime minister since childhood, and he likes winning, but he now finds that he cannot get gratification from those two things at the same time. He cannot enjoy wielding the powers of his office without a majority in parliament, but to acquire one he has to risk losing the office. He has been drawn towards an election since arriving in Downing Street but, thanks to the fixed-term parliaments act, it isn't in his gift to arrange the poll on the terms of his choosing.

Even if Johnson could simply name a date, the optimal moment is hard to discern among all the Brexit variables. His declared preference—expressed in a letter to Jeremy Corbyn—is 12th December, ideally with the withdrawal agreement hastily ratified before dissolution. But the opposition are not going to facilitate a campaign lap-of-honour for a Tory leader boasting that Britain is finally delivered from its European purgatory. Johnson's second preference is a campaign in which he runs as the only man with a workable plan—a deal within touching distance of completion that is obstructed by spiteful parliamentary Remainers.

One hazard in that scenario is that Nigel Farage's Brexit party siphons off Leavers in marginal seats who, in Downing Street's strategic models, are meant to switch from Labour to Tory. Johnson guaranteed liberation on 31st October, “do or die.” He said he would not seek an article 50 extension. Those promises are broken. To mitigate the awkwardness of the betrayal, Downing Street has engaged in diversionary bluster and rhetorical misdirection—sending multiple letters to Brussels; issuing meaningless ultimatums to parliament. But there will be no concealing the mundane facts when EU membership persists on 1st November.

The cabinet is divided on the wisdom of going to the country while Brexit is unresolved. There are weird contingent risks associated with a winter ballot. Voters might not bother turning out in the cold and dark. Gloom might fuel a desire to punish incumbents. But the Downing Street party of war is also impatient to run a head-to-head campaign against Corbyn. There are Labour activists who disbelieve opinion polls and avow that their leader is an electoral asset. That view might one day be vindicated, but Tories mostly see a greater threat posed by the prospect of literally anyone else running as the opposition candidate for prime minister. Most Labour MPs have come to the same conclusion, and the longer the stalemate goes on, the likelier it gets that they might finally do something about it.

The biggest hazard for Johnson is that time spent in office but without power undermines the image he has cultivated as a man of action. Reaching agreement in Brussels was a substantial political achievement. It disoriented opponents whose calculations were based on the impossibility of a deal within the red lines that Downing Street had drawn. The prime minister's haste in erasing those lines, betraying his DUP allies in the process, wrong-footed the opposition. It vindicated the Downing Street method of driving events forwards in an erratic, combative frenzy.

Yet the deal itself is not a good one by any measure used outside the circle of English Eurosceptic puritans. It surrenders access to European markets with no guarantee of equivalent benefits from any direction. Other Tories and some Labour MPs go along with it from sheer fatigue and even they want its most drastic provisions amended. Johnson fears that process for two reasons. First, the coalition of MPs who have signalled provisional support for his deal is too fragile to withstand compromise in any direction. Yielding to moderates chases away hardliners, and vice versa. Second, a period of politicking around the terms of the agreement risks increasing public understanding of its deficiencies and, by extension, those of the man who negotiated them.

Johnson is not equipped to govern through a legislative impasse. He doesn't have the character or patience for it and there is no goodwill in parliament to compensate. He is therefore forced into campaign mode, arming No 10 as the base for rhetorical salvos against his enemies, using the amplifying power of the Downing Street pulpit to try to bully MPs into obedience. This is the natural consequence of having two Boris Johnsons in office and no mandate or majority for either of them. The one who would govern reasonably is always being overruled by the one who campaigns irresponsibly. So if the Commons will not vote for an election, the prime minister will behave as if one is happening anyway.

Rafael Behr is a political columnist for the Guardian