Midlife: A Philosophical Guide Kieran Setiya Princeton , pp. 186 , £

For a long time now, there's been a Stop Boris campaign in operation in Westminster. With the Parliamentary party a lot less keen on the former foreign secretary than the eurosceptic membership, MPs have plotted ways to keep Johnson off the final two in a Tory leadership contest. MPs vote to knock out contenders in Parliamentary rounds before the Tory grassroots select their leader from the two left standing. The way the contest works means that there is ample opportunity for MPs to work together to knock out candidates they don't like.

However, a number of Tory MPs have a new target in their sights. In the past couple of weeks, there has been a sea change in how Tory moderates view Johnson. That’s not because of anything in particular he has done, but because of how they view his main Brexiteer competition: Dominic Raab. As I say in the i paper this week, faced with a choice between Johnson and Raab, a number of Remain-leaning Tories are concluding that BoJo is the least worst option. Rather than “Stop Boris”, the latest operation is “Stop Raab”.

The disastrous EU election results for the Tories – in which Nigel Farage’s Brexit Party stormed to first place and the Conservatives fell into fifth – have cemented in many MPs’ minds the idea that the next leader will have to be a Brexiteer who can take on Farage. Even those Remain-leaning Tories opposed to a no-deal Brexit begrudgingly accept that they may have little say in the matter. The Parliamentary party will work to try and get one candidate in the final two who is not a no-deal Brexiteer. However, they admit privately that this candidate would stand little chance with the membership against a no-deal Brexiteer.

It follows that whichever Brexiteer makes the final two has a very good chance of being the next prime minister. This is why attention has turned of late to stopping Raab. The newly formed “One Nation” caucus of Conservative MPs – made up of Remain-leaning MPs including Nicky Morgan and Dominic Grieve – was reported in some quarters as an effort to stop Johnson. However, one backbencher involved with the group said that faced with a choice, Raab is the one they would find hardest to tolerate.

The reason for the opposition? While Raab has pitched himself as a details man who would put in the work required to take the UK out of the EU, his critics on the left of the party view him in some respects as hardline. Like Johnson, Raab has said he is willing to take the UK out of the EU without a deal come 31 October when the Article 50 extension ends. Only his campaign is viewed as having gone further than Johnson’s - with many MPs doubting whether Johnson would actually go through with a no-deal Brexit.

Raab is regarded as more right wing on domestic politics than Johnson. Some members of the European Research Group of Tory Eurosceptics have long been suspicious of Johnson because they felt his politics did not match their own wholesale. Raab, meanwhile, is a Thatcherite politician who believes in a small state. He has also made a number of comments that have jarred with colleagues – once describing some feminists as 'obnoxious bigots' – and more recently telling the Spectator that he would not describe himself as a feminist.

As one Cabinet minister put it: '[Going from] Cameron to Raab is as bad for us as Blair to Corbyn.' They added: 'Raab doesn’t appeal to any sort of working-class vote, so can’t unlock new voters; while he turns off the voters we already have who will be appalled by his extreme views.' Were Raab to be picked as the Tory leader, one minister has predicted MP resignations: 'There are a whole host of backbenchers threatening to leave the party if he emerges as the winner,' they said.

Raab allies play down the level of opposition to the former Brexit secretary – suggesting that it relates to a handful of MPs rather than a majority. However, for now the movement against Raab is good news for Johnson. Tellingly, a number of Johnson’s critics have softened their opposition to the former mayor of London. The Scottish Conservative leader Ruth Davidson has long been one of his biggest critics but has now insisted that Johnson is someone she could work with after all. This could be crucial for getting Johnson over the line in the Parliamentary rounds.