Boris Johnson’s chances of getting his deal through the House of Commons depend to a very large extent on how he and his main opponent manage internal problems in their respective parties.
The Prime Minister has succeeded in bringing back a deal from the EU27, and unlike his predecessor is leading a party which is far more united in its support for that deal.
Indeed, when voting on Sir Oliver Letwin’s amendment an impressive 98 percent of Conservative MPs followed their leader and opposed it – with the remaining (five MPs) abstaining.
Those are numbers the Prime Minister can be very happy with.
However, that unity has been achieved almost entirely by purging the Conservative Party of dissenters, which means that Boris Johnson is faced with a parliamentary situation not much improved from that faced by Theresa May.
Crunching the numbers does seem to show a (rather narrow) path to getting the legislation to implement the deal through parliament, but it will not take much opposition for that path to close.
This shows the problem of managing Conservative Party divisions on Brexit.
Theresa May’s approach kept (in her case hard-Brexit) dissenters within the party, whereas Boris Johnson has opted to purge the (Brexit sceptical) opponents to his deal.
Neither has so far managed to rally a parliamentary majority behind a Brexit deal. However, Johnson’s approach may yield benefits in the medium term.
By excluding soft-Brexit supporters from the party he may be able to achieve what May failed to do: generate a Conservative parliamentary party which is both united enough and big enough to get his deal over the finish line.
If Johnson fails to get his deal through parliament by 31 October the almost inevitable general election is likely to see candidates more supportive of Johnson’s project replace the purged dissenters.
That would help to further the party unity that Theresa May failed to create.
However, whether Johnson will be able to achieve the majority May also failed to win remains to be seen.
In all this there are limits to what Johnson’s approach to internal party management can achieve.
Johnson is to some extent dependent on how his main opponent – Jeremy Corbyn – manages his party and its divisions.
However, Johnson is in a much better situation than May was in 2017 – partly because Johnson is a much better campaigner than May, but also because the intervening years have not been kind to Corbyn or the Labour Party.
Whilst the parliamentary Labour Party is much more united on Brexit than the Conservatives were pre-purge, Corbyn’s approach to non-Brexit related issues is badly undermining his chances of electoral success.
Corbyn’s response to two key issues has so far served to weaken the Labour Party’s electoral chances: antisemitism and candidate selection challenges.
Louise Ellman’s departure from the Labour Party after 55 years’ membership, and the claim that a Labour councillor who was (briefly) suspended for anti-Semitic remarks is being lined up to take over as parliamentary candidate shows that the Labour Party under Corbyn has not managed to get this poisonous issue under control.
It is very unlikely that any action taken now will manage to reverse, in time for a likely rapidly approaching general election, the damage caused by allegations of antisemitism.
In addition, local Labour Party branches are continuing to vote for full selection processes which open up incumbent MPs to challenge from other would be candidates.
It is true that candidate selection processes do not tend to make much of an impact of public perception of a party – they are generally private and bureaucratic, and thus rarely make for juicy headlines.
However, there are two reasons why these re-selection challenges are problematic for the Labour Party.
One is that of the six MPs who at the time of writing face full selection processes four are women and two are BAME. In absolute numbers this is fairly small, but with the ongoing antisemitism concerns it does add to an impression that Labour has a discrimination problem.
Second, whether facing a full re-selection process or the possibility of one, it is clearly a distraction from the all-important tasks of holding the government to account and preparing for what will be a difficult and extraordinarily important general election.
As the next general election comes ever closer Johnson’s dissenter problem has been largely ‘solved’ as illustrated by the unity on the Letwin amendment.
He may still face ‘hard-Brexit dissent’, but Johnson’s own stance on Brexit should help alleviate that problem.
Johnson still has to solve the ‘majority-in-an-election’ problem, but here he is assisted by the fact that Corbyn’s two main internal problems are very much ongoing.
This puts Johnson is a much better position than Corbyn as the parties increase their campaigning preparations.
By Dr Robin Pettitt, senior lecturer in Comparative Politics, Kingston University London.