It is natural that people who campaign for a political party and identify with its history treat its traditions with a certain reverence. It is also a pattern in British politics that effective party leaders – the ones who win elections – handle those traditions roughly. That is why Boris Johnson is not overly concerned that many Tories think his “health and social care levy” betrays their sacred low-tax creed. He hears the complaint as proof that he belongs in the pantheon of prime ministers who brought new categories of believer to their parties. There could be no Thatcherites without Margaret Thatcher, no Blairites without Blair. The job is already half done in the sense that Johnson’s electoral coalition is built on voters with no previous cultural affiliation to his party. Some had to overcome ancestral aversion to all things Tory. That doesn’t mean those new supporters will be grateful to see their take-home pay go down when the social care levy kicks in. But if they do object, it will have nothing to do with some ideological test of how authentically Conservative or not the policy might be. A question now hanging over the Tories is whether their famous victory in December 2019 indicates a vast and permanent sea change, or a freak tide caused by the gravitational pull when different political planets came into one-off alignment: frustration with Brexit not being done, a Labour party led by Jeremy Corbyn, the “Boris” celebrity factor. Is Johnson rehabilitating the traditional Tory brand or accelerating its rot under the humid cover of his charisma? Opinion polls do not shed much light on the matter because people cannot accurately predict how they would vote in a future election when anything might happen in the interim. But for now, Tories take comfort in Rishi Sunak’s mostly high approval ratings. Political successions are never straightforward, but having a relatively popular chancellor is a rare luxury for a party in its 12th year in government. By contrast, there is no obvious backup leader on Labour’s frontbench and Keir Starmer’s tepid style has yet to inspire great confidence in the party, or much interest elsewhere. After a solid start, his personal ratings took a slide and have now stabilised. They are not disastrous but nor does the trajectory point to Downing Street. He has prime ministerial poise, but no one can say what he is poised to do. The pandemic has not been easy for the opposition. Social restrictions limited the leader’s ability to appear in public. In the heat of a national emergency there was a risk that attacking the government would be perceived as willing it to fail, and thereby siding with the virus. Those constraints, and Starmer’s excuses, expired long ago. He cannot afford to come out of this autumn’s party conference season as limply as he goes into it. Inevitably, Labour’s rival factions have contradictory diagnoses of the malaise and incompatible prescriptions. Much of what comes dressed as a demand to be more radical is really a complaint that the current leader is not enough like his predecessor. Much of what sounds like a demand for new direction is code for a spikier repudiation of Corbyn’s legacy. The indications so far are that Starmer will satisfy neither side by trying to appease both. He is a Labour sentimentalist at heart. Rough handling of party icons is not his style. Such delicacy is good for avoiding confrontation with members but it puts a limit on his ability to reach a wider audience. Most voters are not interested in what it means to be authentically Labour and if Starmer’s pitch is unity on the left, it won’t travel much further. But even a conference speech of soaring majesty might not lift Starmer’s prospects if there is anything more interesting happening that day. (The opposition leader spoke at the TUC annual conference yesterday, setting out some policies to secure workers’ rights. It caused not a ripple on the surface of daytime bulletins, which focused on the prime minister’s Covid winter plan.) Johnson can steal Starmer’s limelight at will, or blunder into it. With Labour bogged down in grey and fretful introspection, the opposition leader is always just a colourful Tory rebellion away from irrelevance. That is partly a failure of political craft in Starmer’s office, but mostly a function of Johnson’s 80-seat majority. If the Tories support the prime minister, he can do pretty much whatever he likes in parliament. Labour voting against it is not news. Only when there is serious dissent on the government side does Starmer get a purchase on the agenda. The social care levy is a case in point. Ahead of its unveiling last week, there was much talk of Tory disquiet. Then whips went to work; a cabinet reshuffle was mooted as a warning shot across the front bench; the government line held. Starmer was fairly criticised for lacking agility and clarity in the attack, but even with a brilliant headlong charge he would have needed Tory MPs to open up a second front. They might still do that as more devilry emerges in the detail of the policy. Shrewd opposition can flush some of that out, but not dictate how Conservatives then react. That reaction is the decisive factor, not just on the social care issue, but in Johnson’s eventual fate. Willingness to remould a party may be a standard feature of successful leadership in British politics, but so is the eventual backlash when those parties get tired of being pushed around. A relevant item here is the list of Tory leaders in modern times who were either removed by their own MPs or debilitated and harried towards defeat by persistent rebellion: all of them. Labour MPs and supporters are not wrong to demand that Starmer get better at fighting Johnson. But there is also a limit to what the opposition leader can achieve when every historical precedent says the prime minister’s waiting nemesis, whoever that may prove to be, is a Tory. Rafael Behr is a Guardian columnist