Even now, months after he was forced to resign, Boris Johnson has a potency that no other British politician can match. Everything he says still catches the attention of Westminster and the media. Like Donald Trump, he enrages his enemies so much that they can seem obsessed. And rumours of a Boris restoration will not go away. ‘If he was six feet under in a coffin,’ says one minister, ‘he’d still have ambitions of a comeback.’ Some MPs do want to see his return to Downing Street, of course. ‘They may be noisy,’ says a member of government. ‘But they’re also small in number.’

Some of Johnson’s critics believe he will only stop being a threat to the government once he is out of parliament. Thanks to the investigation by the House of Commons Privileges Committee, their wish could come true.

By now the whole country knows that during lockdown 10 Downing Street staff were having the sort of social gatherings that had been outlawed for everyone else. The public also knows that Johnson denied any wrongdoing to parliament – it’s one of the main reasons that he is an ex-prime minister. He has already paid a considerable price.

Johnson now admits that he misled parliament but insists he did not do so ‘knowingly or recklessly’. He has sworn to it on the King James Bible. In his 52-page evidence, Johnson says his first reaction to reports about No. 10 parties was that they were ‘some kind of try-on’. Can the committee prove otherwise? Given that Johnson loved to work in a cloud of confusion – it was a strategy to avoid being pinned down – it’s a hard task. Any verdict will be controversial.

Johnson’s supporters have been quick to accuse MPs on the committee of presiding over a show trial. ‘His team has done a lot of work to shape the narrative to create that of a witch-hunt,’ explains one Tory. In a bid to boost camaraderie, Johnson’s allies are telling parliamentary colleagues that an attack on Johnson is an attack on the party: if they let this stand, they say, others will be next. Keir Starmer’s plan to appoint Sue Gray – the senior civil servant who authored the original partygate investigation – as chief of staff has added to claims that Johnson is the victim of a partisan process.

The stakes are high. If Johnson is found guilty of knowingly misleading parliament, he could be the first former prime minister in history to be forced out in a ‘recall’ petition. If he is suspended for ten, rather than seven, sitting days he’s vulnerable to a constituent petition which would force a by-election. On current polling, Johnson (whose majority is around 7,000) would lose.

While some Tories would like nothing more than for Johnson to lose his seat, others worry that it would lead to more party infighting. For now, No. 10 is more nervous about the consequences of a Johnson banishment than his potential comeback. One cabinet minister insists that a Johnson return would quickly disintegrate: ‘The party wouldn’t wear it.’ A poll for Conservative Home of Tory members found that while there was sympathy for Johnson and a belief that he should be a candidate at the next election, two-thirds of members don’t want him back in No. 10. Johnson’s supporters are more focused on attacking Kemi Badenoch, the business and trade secretary, whom bookmakers have as the main contender to succeed Rishi Sunak. Johnsonites have been sharing screengrabs of texts from her appearing to encourage Tory colleagues to resign in the final days of Johnson’s reign.

Even without an immediate challenge to Sunak’s premiership, the Privileges Committee soap opera, which is expected to span months and could run during the local elections, is bad news for a government that’s trying to move on from scandal. The No. 10 approach is to try not to feed the frenzy, but it’s not a coincidence that many of the rebels in the vote on the Prime Minister’s Brexit deal are Johnson loyalists. In a pre-local elections briefing, the pollster Lord Hayward said partygate continued to have a negative effect even if that effect was diminishing. The fact that Sunak called off plans to release anti-social behaviour policies this week is a sign of how he can struggle to compete with his predecessors for news coverage.

No. 10’s strategy is to pitch Sunak as a fresh face – so the next election would be about the first Sunak term, not a fifth Tory term. ‘But we’re being sucked back in to scandal,’ complains one disheartened minister. As well as Johnson appearing before the committee, the beleaguered cabinet secretary Simon Case could be asked to give evidence. So could Dominic Cummings, Johnson’s aide-turned-nemesis.

Already the row has reopened the pair’s feud, with Johnson arguing that Cummings ‘cannot be treated as a credible witness’ due to his ‘animus towards me’. Cummings has hit back, accusing Johnson of ‘further misinformation’ and promising a running commentary on the whole show. ‘Part of the reason we got rid of Boris was to end this psychodrama,’ says one member of the 2019 intake.

The final punishment could prove the most painful. If Johnson faces a ten-day suspension, the decision would go to a free vote of MPs. Scarred by the Owen Paterson debacle, when MPs were whipped to vote against such a punishment only to have to change tack, no one but the most hardline Johnson supporters would reject the report’s recommendations. Others could abstain. A cabinet divide would emerge as a Johnson loyalty test gets under way. Potential Sunak successors such as the Home Secretary, Suella Braverman, could see the appeal of keeping the grassroots on side.

If a ‘recall’ petition succeeds, Sunak would be under pressure to back Johnson and throw resources into the by-election. ‘He couldn’t not go up there and campaign,’ says one senior Tory MP. Were Johnson to hold his seat, his supporters would say his victory proves he is still an election winner. Were he to lose, he could be spun as a martyr: a Brexit champion finally brought down by the establishment. Sunak’s best hope is that the inquiry ends fast and Johnson avoids a suspension that extends the Boris circus – and the Tory party’s misery.