The stand-off between Downing Street and the European Union over Boris Johnson's latest proposal for the backstop boils down to a disagreement over whether the British government really cares about getting a Brexit deal at all. When Donald Tusk rejected Johnson's plan today, he all but accused him of being set on a no-deal exit, saying: 'The backstop is an insurance to avoid a hard border on the island of Ireland unless and until an alternative is found. Those against the backstop and not proposing realistic alternatives in fact support re-establishing a border. Even if they do not admit it.'

A Downing Street spokesperson hit back at this, insisting that 'we are ready to negotiate, in good faith, an alternative to the backstop, with provisions to ensure that the Irish border issues are dealt with where they should always have been: in the negotiations on the future agreement between the UK and the EU'.

Johnson's plan, which he announced last night, rejects the backstop as 'anti-democratic', 'inconsistent with the UK's desired final destination for a sustainable long-term relationship with the EU' and a risk to the 'delicate balance embodied in the Belfast (Good Friday) Agreement'. He will have meetings this week with Angela Merkel and Emmanuel Macron to discuss his demands for a deal.

The EU might cave from its current position on the backstop as 31 October approaches and no deal becomes more likely. But the battle at the moment is as much for control of the narrative as anything else. For Johnson, it is important to have someone else to blame for any chaos that does follow Britain leaving without a deal. It will be much easier to do if he has given the appearance of negotiating seriously and can therefore say that the European Union pushed Britain to leave in this way. Tusk, meanwhile, needs to get out a message that Johnson doesn't actually want a deal and is just throwing up random and unworkable suggestions which he knows the EU would never accept in a million years.

So much of the Brexit debate over the past couple of months has been about who to blame for the delays and disagreements. Now we are approaching the end of that blame game, and things are heating up.