Jeremy Corbyn and Dominic Grieve.

The parallel between his situation and that of many pre-Corbyn Labour MPs is uncanny but slightly misleading. Yes, the attempt to deselect him is being led by someone who was recently a member of a rival party – in his case someone who stood as the Ukip candidate against him at the last election. Just as many of the noisiest advocates of deselecting “Blairite” Labour MPs are fresh from rival parties such as the Greens or sundry Trotskyist organisations.

And the push to deselect Tory MPs is a mirror image of the puritanism of the Corbynites, valuing ideological conformity over coalition-building. Sam Gyimah, another Tory MP who wants to keep Britain in the EU, saw off an attempt by his local party to censure him last week. Even Nick Boles, the Grantham MP who supports the prime minister’s deal but who is seen as soft on Brexit, now sits as a Tory MP who is a member of the party nationally but not locally.

The fate of Grieve, Gyimah and Boles is a sign of the realignment of politics. The parties are being reshaped around new poles, but this is about Europe and has nothing to do with the ideology of Corbynism.  

The Conservatives are becoming the Brexit party, while Labour is becoming ever more emphatically the party of Remain, a cause about which Jeremy Corbyn has little to say. If we leave the EU, the Labour leader’s bet-hedging will allow him to move on and change the subject. Once we are out, Labour would not become the party of “rejoin” – the Independent Group, now called Change UK, the Liberal Democrats and the Scottish National Party can do that.

The significance of this week’s vote against the withdrawal agreement is that we are likely to be staying in the EU for the foreseeable future. There might in the next 13 days be a fourth and even a fifth vote on the withdrawal agreement, possibly with changes to the accompanying political declaration. If it passes, I think the EU would still allow us to leave on 22 May, but in my view the chances of that are now about 30 per cent. If it doesn’t pass, I don’t think we will leave without a deal – neither side wants that – and so we will probably be granted a long extension to at least the end of the year.

Then it will not be possible for Corbyn to change the subject and move on. The cleavage over Europe will continue to be the main subject of public contention, not least because the first consequence of staying in the EU is that we hold elections for the European Parliament.

That is a great opportunity for the two ends of the increasingly polarised spectrum. At the Remain end: Change UK, which has applied to register as a political party under interim leader Heidi Allen. It must hope to copy the success of the Green Party in 1989 and Ukip in 2014.

At the Leave end: Nigel Farage’s new Brexit party, Ukip reincarnated, although it will face competition from the other Brexit party, the Conservatives. The contest will be between the fundamentalists at both ends – between those who want to cancel Brexit altogether and those who will cry betrayal, condemn the “coup by the elite against the people”, and demand a clean, no-deal Brexit. This is what politics could be like. The Conservatives will move to take up the hard-Brexit space occupied by Farage – we have seen that manoeuvre before. And Labour will move to take up the Remain space to head off the challenge from Change UK – ironically by opposing change to our membership of the EU.

It is all too possible that we will never leave the EU – and that we will never stop arguing about it.