Henry Newman is Director of Open Europe.

In a little over two weeks’ time, Boris Johnson will – barring a huge upset – become Prime Minister. He will face enormous political difficulties, as the Conservatives struggle to cling to office with a precarious parliamentary position.

His predecessor managed a year-long honeymoon before imploding with catastrophic consequences in the snap general election which destroyed her chances of success on Brexit or indeed much else. Johnson will have far less time. There’s barely three months before the October 31st Brexit deadline which he himself has described as “do or die”.

The stakes are extraordinarily high, and not just for his administration but the Conservative Party itself, which now faces what seems like an existential threat. Everything will rest of the decisions Johnson takes in his first few days in office – on the appointment of his top team, what he says to his parliamentary colleagues about his plans for Brexit, and how he shapes his Brexit policy.

Although we have heard far more recently from him than we did in the early stages of the leadership race, there are still big question marks over many areas of his plans for Brexit. He insisted over the weekend that he was not “bluffing” over the possibility of a No Deal Brexit on October 31st, having previously described the odds of one as a “million-to-one against”. There are significant differences in the positions espoused by different members of his team or their outriders. Some talk of tearing up the current deal, others more in terms of tweaks. This may or may not be part of a strategy of creative ambiguity, keeping options open for later on in the process.

Delivering Brexit by October 31st will be a very significant challenge. Europe is largely out of action for August, with a long summer break. But more importantly, the European Council – where heads of governments and states from across the EU meet – is not scheduled to gather until 17th and 18th October. That’s less than a fortnight before exit date, leaving hardly any time for Parliament to pass a deal, even assuming new concessions could be secured. When I asked civil servants whether the requisite legislation could be bashed through in that time, they blanched. It might be possible to arrange an emergency Council meeting before mid-October, but leaders will be reluctant to do so. A serious charm offensive will be required.

Officials and politicians from key EU member states continue to argue publicly that the Brexit deal is closed. They repeat their mantra that the Withdrawal Agreement is not up for renegotiation. On the other hand, there’s also an acceptance that a new prime minister does need to be given a hearing in Brussels. Although it’s obvious to all that the exact same deal now stands no chance of passing Parliament, this has not yet led to a push from the EU side to make further concessions to the UK.

EU leaders will be loath to concede much to Johnson, whom they see as something of a bogeyman. A few weeks ago, European diplomats told my team that the EU would be less likely to make concessions to what they called ‘Hard Brexit’ candidates such as Dominic Raab or Johnson, as opposed to other potential prime ministers. But finding a negotiated way through on Brexit, and agreeing a stable framework for long-term cooperation with the Continent’s second biggest economy and most important defence and security player, ought to be a top priority for the EU, whoever is in charge in Westminster.

The decision on whether to move or not on Brexit concessions will really come down to three key capitals – the EU27’s pre-eminent powers, Paris and Berlin, of course, but also Dublin. Because if the Irish signal they can accept an attenuated form of the backstop, other member states would likely go along with them. The Irish Foreign Minister did acknowledge yesterday the (obvious) point that “No Deal means we lose the backstop”. But there’s no sign yet of Ireland preferring a time limited backstop to the possibility of no backstop at all on October 31st.

Amongst the first decisions for a new Prime Minister is the formation of their cabinet. So much of the shape of Theresa May’s time in office was fixed by her early decisions in building her team – whether Nick Timothy and Fiona Hill (her powerful Chiefs of Staff), or Philip Hammond, the Chancellor she was never strong enough to fire, despite her apparent wish to do so a year later.

Every leader is tempted to appoint allies to fill their Cabinet. But that’s a risky approach even at the best of times. It’s particularly difficult given the hung parliament, and the polarisation within the Conservative Party. There’s now a serious risk of the Government being brought down – or at least made impotent – by two blocs of its own MPs. On one side of the party, self-declared Spartans threaten to withdraw support if Brexit does not happen on time or in the right form; at the other end of the spectrum, a similarly-sized group seeks to prevent a No Deal Brexit, with some threatening to do so at any cost.

Johnson will need both of these blocs to survive in office. So he should model his Cabinet on the team of rivals approach adopted by Abraham Lincoln. Given his clarity on the issue of the Brexit deadline, he has understandably decided to ask all new cabinet minister to commit to leaving the EU by 31st October. This will rule out several big beasts, meaning the backbenches could be home to some potential rivals, which he will need to manage.

Another big problem facing the new leader is the gap between the expectations of what is possible on Brexit, and the reality of what is likely to be secured. On the plus side though, Johnson’s rhetorical abilities and political salesmanship skills far eclipses Theresa May’s wooden communication style. May was not just bad at making the case for her Brexit deal, for too long it seemed as if she was not even trying to do so. Johnson must not make that same mistake.

The new occupant of 10 Downing Street will face a bumpy few months ahead. At the same time as getting Government on a full No Deal footing, he must prepare for a possible forced general election, retain the support of the DUP as well as recalcitrant Tory colleagues, launch a Brexit charm offensive in Europe, and face a host of domestic problems requiring urgent attention. That’s a very full ‘In Tray’.

Meanwhile, the Conservative Party risks destroying its reputation for good governance if it continues to air its dirty laundry in public and fails to pull together on Brexit. As leader, Johnson should set out to bring the whole party back together whether supporters of his or opponents, Leavers or Remainers, Brexit Spartans or anti-No Dealers. For their part, all Conservative MPs should give him the chance to do so. There’s a path through to delivering Brexit. It’s painfully narrow. It can be reached…just. But only if Conservative MPs and the new Prime Minister all work together.