As Rishi Sunak concludes tortuous NI deal, Boris Johnson watches and waits

Rishi Sunak is approaching what might be his toughest party management challenge yet – the conclusion of a long negotiation to find a way through the tortuous issue of the Northern Ireland protocol.

But his being able to his MPs in line is likely to depend hugely on whether Boris Johnson sees the protocol as his moment to stage a key intervention that could launch a potential comeback.

Those who have spoken to the former prime minister say he will consider his options very carefully when the shape of the deal is obvious, before judging whether it would be the right time to force a new major division in the party.

Without the Johnson problem, there is much in Sunak’s favour. He has one of the easiest political climates to make a deal with Brussels. In polling on voter priorities, the UK’s relationship with the EU is now rock bottom for many voters – just 17%, compared with 72% in 2019.

For all but the most fervent rejoiners and hardcore Brexiters who crave a betrayal narrative, the most pressing problems for the country are the economy and the health service – though many remainers would argue the issues facing both are closely linked to Brexit.

He also may have an easier ride in parliament – sources suggest that the agreement on customs and judicial oversight may not involve a reopening of the protocol or the treaty and therefore not require a parliamentary vote.

Sunak may still decide to hold one to show he has the resolve – he did so over cutting the international aid budget – but he would have no problem passing his deal because Labour has made it clear it will support a sensible compromise.

There are still enough MPs who are incensed enough by a potential role for the European court of justice in any deal to cause damage to Sunak, and any vote will depend on his willingness to risk his authority in the party to secure the deal.

But the Brexiter wing is not the force it once was. Two of Sunak’s predecessors, David Cameron and Theresa May, were eventually brought down by the power of the European Research Group of Brexiter MPs. Under May in particular, they acted almost as a shadow government, with a whipping system, media briefings and devising alternative legislation.

The ERG is not entirely diminished and still has figures at the helm who are respected by their colleagues – Sir Bill Cash and the former Brexit minister David Jones. It was also decisive in the victory of Liz Truss over Sunak, endorsing her as the true Brexiter heir despite Truss having voted remain and Sunak leave.

But the group no longer has the political operators like Steve Baker, who is now a Northern Ireland minister and a reformed “hard man” who wants to seek a peaceful resolution. Jacob Rees-Mogg is keeping his own powder dry on the issue too.

The chief whip, Simon Hart, has been making significant efforts to keep in close touch with potential rebels on the protocol and to keep No 10 well informed on the numbers and what solutions would be acceptable.

His approach to party management has been to identify other policy areas where there are potentially threatening rebellions – including onshore wind, planning reform and online harms – and offer compromises.

Particularly on housebuilding targets, Sunak could have bulldozed through the rebels and seen off the issue on the back of Labour votes but chose not to – prioritising party unity. It is clear that Sunak wants to only have the fights when they are deemed to be really worth having. Government sources have suggested that comes down to the protocol, immigration and strikes laws.

There have also been attempts to woo potentially rebellious rightwing MPs with a hard line on immigration in recent weeks, including briefings about the possibility of leaving the European convention on human rights and a new bill being prepared severely curtailing the rights to claim asylum.

For many red wall MPs whose inboxes are full of voter anger over boats crossing the Channel – no matter how far those constituencies are from the Kent coast – that is a more pressing voter priority. And it is also the issue more likely to see off the threat of the Reform party and the potential return of Nigel Farage, rather than Brexit technicalities.

But there are whisperings even from supportive MPs that Sunak might still find his authority dwindling by a well-timed Johnson intervention and by swerving a vote in parliament or a reliance on Labour votes to pass any compromise.

Ultimately, Sunak still has a mandate problem – with none from the country or the party but only from his MPs. Should he lose his majority over the protocol and be forced to use Labour support, it will be a moment for Johnson to remind the party of the alternative mandate he holds.