There is a growing feeling in the Conservative party that Boris Johnson’s performance as prime minister would be much improved by him being a bit less Boris Johnson. MPs don’t express the thought in those terms. They praise their leader’s winning ways with voters but regret that his agenda is unfocused. They are thankful for the boost that Covid vaccinations gave to their poll ratings but grumble that the dividend is being squandered while tough decisions go unmade. They admire Johnson’s way with words but despair of the way he mismanages people. Every policy dish comes slathered in rhetorical condiment – “levelling up” was the “ketchup of catch-up” last week – with no meat underneath. This week there is a stew of initiatives targeting crime and antisocial behaviour: more tagging and CCTV, offenders on litter-picking duty, extended stop-and-search. The Police Federation, aggrieved over frozen pay, dismisses it as gimmickry. It will not satisfy Tory MPs’ hunger for substance. They should know the menu by now. Johnson cannot deliver strategic diligence any more than Theresa May could dazzle with dextrous wit. It doesn’t come naturally and can’t be faked. The Conservative party chose its current leader precisely because he was uninterested in the practical reality of government. May failed because she tried to get Brexit done in some meaningful, technical sense. Johnson triumphed by getting it done in the realm of pure imagination and carrying with him a lot of people who couldn’t conceive of voting Tory under anyone else. There is tension between the election-winning force that is “Boris” – a one-off phenomenon – and the Conservative party as an institution that would like to have a future in government under less capricious leadership. It is easy to forget that there were two nationwide ballots in 2019 and the Tories were humiliated in the first one – the European parliamentary election in which they came fifth, behind the Greens, Labour, Liberal Democrats and, in first place, the Brexit party. That was a wild result in extreme conditions, but it was hardly the first time British voters have registered an interest in breaking up the two main parties’ duopoly. It is already broken beyond repair in Scotland. David Cameron thought the political pendulum was swinging his way in 2010, only to find it snagged on a spike in support for the Lib Dems. Their tenacity as a third-party spoiler is itself a legacy of the SDP’s brief breakthrough in the 1980s. The failure of that schism to break the two-party mould is what persuaded many opponents of Jeremy Corbyn to stick with Labour even when they felt their party had been captured by dangerous fanatics. Some moderates quit on points of principle. Most sat tight and waited for the Corbynite tide to recede. But the high waters swept in tens of thousands of new members, with the result that Labour became, in effect, two parties – one for moderate social democrats, and a radical socialist challenger. In continental European countries with proportional electoral systems, no one expects those two tribes to live under one roof. The same is true of the national populists and orthodox conservatives who mingle under Johnson’s banner. The Tories solved their Brexit party problem by total assimilation, and some MPs argue that this is a sustainable arrangement. The prime minister, they say, is charting a new centre ground. He leans left on economics (borrowing money to spend on stuff voters like) and veers right on cultural values (extending the perpetual crackdown on immigration). That upsets small-state Thatcherites, fiscal hawks and social liberals, but it ticks enough boxes with the public to lock the opposition out of power for another term at least. Another view is that only a “Boris effect” glues together an improbable alliance of ex-Labour stalwarts, shire Tories and people who simply couldn’t stomach the idea of Corbyn as prime minister. In that interpretation, there is no alchemy of a new centre ground and no roadmap there for 21st-century Conservatism: just old-fashioned charisma, plus luck. It is hard to know either way because allegiances have been so volatile in recent years. In the aftermath of the Brexit referendum, leaver and remainer identities seemed to have trumped previous loyalties. Tory pro-Europeans met Labour’s anti-Corbyn faction in a symmetrical centrist recoil from their respective leaders. “None of the above” soared in opinion polls. Whips lost control of their parties. MPs switched sides or declared themselves independent. But when it came to the 2017 and 2019 general elections, first past the post and the question of who should be prime minister had their usual effect. When only two parties can credibly claim to be running candidates for No 10, votes get funnelled back down the old red and blue channels. In the absence of electoral reform there is no obvious reason why the pattern will change. And yet it is unhealthy and unstable for the country’s two big parties to be sustained only by polarising mutual animosity and a system that suffocates political startups. That is how we now have a Labour party where admirers of Corbyn in exile cohabit with supporters of the successor who banished him. That is how we have a Conservative prime minister whose superpower is persuading people to overlook the fact that he is a Tory. It suits Labour and the Tories to tell people that each is the only alternative to the other. It suits them to pretend that votes cast under those conditions indicate popular support. But it insults the intelligence of everyone who held their noses in 2019 and marked the ballot paper with fists clenched in frustration at the choice on offer. There is less surface volatility now, but the deeper currents are, I suspect, still turbulent. The two big political brands have primacy in a failed marketplace. It is not easy to envisage what the force will be that disrupts their arrangement. But that is the nature of dramatic change. It is unimaginable right up until it happens, at which point everyone agrees that it was inevitable. Rafael Behr is a Guardian columnist