Voices: Boris Johnson loves fighting the Brexit war – but the Tories have stopped following his lead

Boris Johnson’s decision to vote against Rishi Sunak’s deal with the EU on the Northern Ireland protocol is an act of sheer opportunism. Again, Johnson is in denial: Sunak has secured a better agreement for the province than he ever did, as even some Tory Eurosceptics concede.

Sunak is clearing up the mess left by Johnson conceding a trade border in the Irish Sea and then denying it. The new Windsor framework allows the Northern Ireland assembly to apply a “brake” on future single-market regulations in the province. It is as good a deal as the UK is ever going to get from the EU.

Johnson has argued that Sunak’s deal is “not acceptable”, as it would mean either that Northern Ireland is “increasingly divergent from the rest of the UK” or that the UK is unable to diverge from the EU. He claimed the best course is his legislation allowing the UK to overturn parts of the protocol, a move that might end in a mutually damaging trade war with the EU rather than the peace, better relations and reduced trade friction Sunak’s deal offers.

Liz Truss joined Johnson in voting against the deal in the Commons. Anyone would think they didn’t wish their successor well. Surely that can’t be right?

Of course it is. Johnson seems intent on doing everything he can to undermine Sunak, in the hope he can survive the privileges committee inquiry into whether he knowingly lied to parliament over Partygate and make a remarkable comeback to save the Tories from electoral defeat next year.

Johnson’s and Truss’ move encouraged a few of their remaining followers to vote against Sunak’s deal in the Commons this afternoon. But by the Eurosceptics’ standards, a rebellion by 22 Tory MPs was pretty small beer. It was a sign that many Tories have tired of fighting the last war on Brexit. Sunak’s deal was approved by 515 votes to 29. Crucially, his victory did not rely on the votes of the Labour opposition, which would have been uncomfortable.

As ever, “Boris and Brexit” are inextricably linked. The Commons vote on Sunak’s deal will come during Johnson’s grilling by the committee. Although Sunak allies insist this is a coincidence, no one at Westminster really believes it. If you can’t bury bad news – and the Johnson circus coming to town is undoubtedly that for Sunak – then it’s best to get two dollops of it out of the way on the same day. This will deny Johnson another day of the attention he still craves.

Although Johnson’s ability to command headlines has not waned, his support among Tory MPs has since he mustered 100 of them for a possible comeback when Truss resigned, before deciding not to run against Sunak. The current prime minister’s good run in recent weeks has tipped the scales against a Johnson return. “There is a growing sense that Boris has had his day,” one senior Tory backbencher told me. “The return of Partygate is a warning that we would be mad to go back to all that.” A former Johnson ally added: “We have to recognise that the world has moved on.”

Even grassroots Tory members who sympathise with Johnson over the Partygate inquiry no longer want him back in Downing Street. Only one in four wants a comeback before the election, and two-thirds do not, according to a ConservativeHome survey.

Johnson is a Marmite figure for the public but Robert Hayward, the Tory peer and elections expert, said a Johnson return would transform the party’s election chances “in a negative way, not in a positive way”. He warned that voters would not accept yet another change of PM before the election.

Tory MPs should take note: they have a chance to move on from both Johnson and the Brexit wars by rallying behind Sunak – their party’s best hope of a surprise election victory.

They should dismiss the rumblings against Sunak’s agreement from the dinosaurs in the European Research Group, whose numbers are dwindling as they head for extinction. Although some Tory Brexiteers took their cue from the Democratic Unionist Party, six of whose eight MPs voted against the agreement, the party’s leader Jeffrey Donaldson’s words are softer than the headlines suggest.

Ministers hope the DUP might yet re-join Northern Ireland’s mothballed devolved government after local elections in May. There is a good reason to: if the assembly is not sitting, the “brake” on future EU rules could not be triggered so they would go ahead. Whitehall sources tell me Sunak might offer the DUP more assurances – for example, a guarantee the UK government would always apply the “brake” if the assembly requested it.

Tory MPs will make up their own minds on Partygate in a free vote, but should not be tempted to rescue Johnson if the privileges committee finds he knowingly misled parliament. Reminder: his attempt in the Commons to overturn a ruling that his ally Owen Paterson broke lobbying rules was the start of Johnson’s downfall. At the time, he was riding high and talking about 10 years in power. He was out in less than 10 months.

The Tories should be wary of distracting from Sunak’s recent solid performance. His good run has now been extended by the Commons’ approval of his EU deal. The 22 rebels could still prove an awkward squad. But flirting with a Johnson comeback would be evidence of a death wish, not a survival instinct. Sunak allies rightly point out that the narrow path to a fifth Tory victory is predicated on party unity. If they want to win, Tory MPs need to put the chaos and divisions caused by "Boris and Brexit" behind them.