Boris Johnson’s entire life and career are littered with personal, professional and political deceptions. He breaks rules and tells lies with shameless confidence and without compunction. This is part of his act, but it sometimes feels as if it is almost a matter of self-regarding principle too. That is partly because, most of the time, he gets away with and is even rewarded for it. So why should it be any different now? The question facing British politics today is whether the image of a Downing Street Christmas party, and the excruciating insensitivity there would be in holding it on a day when nearly 500 people were dying of Covid, may be the event to burst Johnson’s bubble. Last week an online video spoof showed Johnson apparently receiving a Covid booster jab, then shrivelling up like an empty balloon. That video was someone’s fantasy. Now nature is imitating art. It was a deflated Johnson, a rare sight in any season, who turned up to answer prime minister’s questions on Wednesday. ITV’s toe-curling video of staffers smirking and joking about the party is the real thing, not a spoof. The reality it portrayed is likely to lodge in the collective mind. In less than a minute, the video captures all the shallow amateurism of modern politics: its absence of moral awareness, its capacity for awful judgment and its corrosive sense of entitlement, acted out against the backdrop of a wholly unnecessary, flag-draped new briefing room that is an expensive monument to a man-child prime minister’s ego and his absurd great-man view of himself. Does anyone wonder that public trust in politics is plumbing new depths, according to a report this week? The video certainly scared ministers off the airwaves for a while, leaving the government undefended against some genuinely cutting attacks from Labour and the Tory backbenchers. It left Johnson with no immediate alternative but to grit his teeth, try to look contrite and apologise, up to a point and uncharacteristically. He managed to take the political punches in the Commons without losing his rag and making things worse, but the damage was plain to see on the Tory benches. In the short term, Johnson now has three main options in this crisis. The first is to attempt to kick the Christmas party controversy into the long grass. He did this by the time-honoured expedient of referring the whole thing to an inquiry by the cabinet secretary, Simon Case. Johnson will feel he can pick and choose his response to any embarrassing findings here, as he did with the Priti Patel bullying case. He certainly does not want a police probe, which would be far more threatening, and Keir Starmer was smart to entrap Johnson into keeping that possibility alive. The second weapon is to create a headline-grabbing distraction of some kind. In an ideal Johnsonian world he would have done this by picking another fight with liberals over an issue like the Human Rights Act. But he is on the back foot now. It is a mark of the hand-to-mouth urgency of his present battle for survival that Johnson was forced to choose Covid restrictions as his diversionary tactic, an issue that divides his MPs, which he has consistently mishandled in the past, and on which his authority is now even further diminished because of the ITV revelations. The problem for Johnson is that this will blunt his third key weapon, the need to demand the support and loyalty of Tory MPs in helping the party and government through the furore. The response in Tory ranks matters most and will hold the key. The backbench response was bad enough for Johnson – there was talk of serious upset, tipping points, Barnard Castle moments and even apocalypse. There were gaps on the Tory benches during PMQs too, another sign of disaffection. But that is as nothing to the mood that would follow the loss of the North Shropshire byelection next week. It isn’t just that North Shropshire is a rock-solid Conservative bastion that in its current and earlier incarnations has returned a Tory at every election in the last 115 years (even unopposed in 1935). It isn’t just that this byelection was triggered by Johnson’s stupid attempt to bully the Commons into changing its standards regime to suit Owen Paterson, who promptly resigned the seat. It is that local rivalry between the opposition parties means a win for either the Liberal Democrats or Labour would be genuinely astonishing. It would be the loss of a seat. But it would also feel like evidence of a tactical-voting dagger pointed at the hearts of dozens and dozens of other Tory MPs. If North Shropshire falls, this week’s sullen impatience with Johnson could escalate quickly – even over the Christmas break. That is why this time things may indeed be different for Johnson. Partly because it is serious – perhaps even involving lawbreaking. Partly because the joke may not be funny any more, with the polls suggesting that voters have begun to tire of Johnson’s act. Partly because the whole episode reveals a prime minister, not to mention a former Downing Street press secretary, who is simply out of his depth. And finally, because the country may be on its quiet, midterm way to concluding not just that it needs a new government but that there may be a plausible alternative. None of this is remotely set in stone. The damage that politics has done to itself over many years, especially under Johnson, is very disabling, and not just to the Tory cause. Labour is only recovering slowly, and bright new dawns are not currently on offer. But the sense that the country can do better than this, can be better governed than this, that it needs to come together and not grow more divided, that it can find fairer and steadier ways of dealing with serious problems, not least in its wounded democracy, runs very deep. Johnson’s way is emphatically now part of the problem, not part of any solution. On that, I think, the wheel has begun to turn. Martin Kettle is a Guardian columnist