During the summer leadership race between Rishi Sunak and Liz Truss, Sunak’s team were braced for a bloodbath if he won. It would have required a major polling error and gone down as one of the biggest political upsets in recent years. ‘If we win, we win by 1 per cent,’ was how one close ally of Sunak put it at the time.

If this had played out, it would have come as a nasty surprise to many in the Tory party. With wounds still raw from Boris Johnson’s departure, the deposed former PM’s loyalists would have quickly gone on the offensive – accusing Sunak of being a traitor for resigning in Johnson’s dying days. Supporters of Truss, meanwhile, would have claimed the tiny win meant that he didn’t have a mandate for his fiscal plan and pushed instead for immediate tax cuts. The prospect of these rebels in the event of a slim Sunak victory was so bad that it led some MPs in the middle of the party to vote for Truss.

Fast-forward six weeks, however, and Sunak finds himself in a rather different position, having won the support of more than half the parliamentary party. Of course the various crises facing the country have grown since September, but Sunak no longer faces the same amount of volatility in managing the party. ‘It’s gone from near impossible to very difficult,’ says one figure who worked on Sunak’s summer campaign.

Sunak has been helped by the fact that there aren’t that many hardcore Johnson loyalists left after the former prime minister’s abandoned attempt at returning to No. 10. When Johnson announced he was pulling out of the race, many of his key backers – including Priti Patel and James Duddridge, who ran the campaign – switched their allegiances to Sunak. ‘It’s really only a couple of ultras still holding out against Rishi,’ said one senior Tory. While Johnson’s cheerleader-in-chief Nadine Dorries has wasted no time in criticising Sunak’s appointment – arguing that he has no mandate and branding his reshuffle ‘underwhelming’ – the majority of Johnson backers are keeping their powder dry.

After a year of vicious infighting there is a sense within the party that they need to move forward. As the new Prime Minister put it in his first address to MPs, they face a choice: unite or die. But achieving unity is a harder task than simply saying you want it. Sunak’s team are acutely aware that a party that has deposed two leaders in the space of four months will be hard to keep on side – particularly with the multiple challenges looming.

In this vein, Sunak’s team are on a mission to avoid repeating the mistakes of the Truss premiership. While loyalty is a key trait in Sunak’s No. 10 team – with senior positions going to those who worked for him in the Treasury and then on his campaign – the reshuffle was meant to serve as an exercise in reaching out to all wings of the party.

Truss handed the most senior ministerial roles to those who had backed her in the contest. In contrast, Sunak has retained a mix of Boris backers (Ben Wallace and Nadhim Zahawi) and Trussites (James Cleverly and Thérèse Coffey). Though the return of Suella Braverman to the Home Office just six days after she was forced to resign over a security breach has worried both the Truss camp and senior backbenchers. ‘You can’t say you stand for integrity on the same day you do that,’ says one perturbed Tory MP.

The appointment is a sign that Sunak is becoming more political. Ultimately, Braverman is viewed as key to keeping the right wing of the party behind him. It was her endorsement of Sunak over Johnson that led many MPs to conclude the contest was a done deal. ‘If you want to keep the right of the party on side, you need Suella,’ says one Sunak ally.

Had Sunak won in the summer, Jeremy Hunt would not have been his choice for chancellor. The situation he inherited this week means that his team concluded keeping Hunt in No. 11 was the safest option. But where Truss had to effectively cede control of financial decisions to Hunt, the relationship between the new Prime Minister and Chancellor will be the other way round. Already the pair have agreed to delay the Halloween fiscal event from 31 October to 17 November. The thinking is that the new government ought to take time to work out where spending cuts and potential tax rises are best placed. It’s these decisions that will shape the narrative around Sunak’s government – and on which the public, and MPs, will judge them.

Since the summer, the fiscal black hole has grown. It means difficult decisions are coming that some in the party may not like. The Defence Secretary, Ben Wallace, wants defence spending increased to 3 per cent. New Foreign Office minister Andrew Mitchell is a passionate supporter of maintaining the international aid budget. The new Work and Pensions Secretary, Mel Stride, has suggested benefits should rise in line with inflation. All demands could now be hard to meet. The hope is that ministers will help to sell any tricky decisions to MPs and the public.

Labour is already sharpening up its attack lines. Party figures openly admit that Truss was their preferred opponent – even if some in the party are dismissive of Sunak. ‘I’ve been ready for Rishi for years,’ says one member of the front bench. ‘He’s one of the most overrated politicians in Westminster.’

Regardless, Keir Starmer wants his party to be prepared. They are planning to depict Sunak as ‘ruthless’ and someone who ‘stabbed Boris Johnson in the back’ just as the Tories argued Ed Miliband did to his brother, David. Labour will seek to tie Sunak to past government decisions – suggesting he has played a key role in the worsening economic outlook.

But as displayed in his first speech outside Downing Street, Sunak has his own card to play. He told the nation he was there to fix the ‘mistakes’ made under Truss’s leadership. Sunak is trying to use the differences between him and his predecessor to his advantage. Whether Sunak can maintain party unity will define his time in office.