One of the main messages that Theresa May is taking to Brussels today is that significant, legally binding changes to the backstop are needed to get the withdrawal agreement through the House of Commons. Jeremy Corbyn’s letter to her undermines that position. In it, the Labour leader sounds less hostile to the backstop than he did after meeting May last week. Instead, he suggests that the way to deal with the backstop issue is through a political declaration that makes it much less likely that it has to be used. This is the EU’s preferred solution too, and so Corbyn’s offer undercuts the message that May is trying to take to Brussels.
I suspect that EU leaders will be quick to tell May that Corbyn’s offer means that there’s an alternative parliamentary majority for the withdrawal agreement. May, of course, won’t want to take Corbyn up on his offer because it is designed to split the Tories in two. May, who joined the party as a teenager, has no desire to become the Tory answer to Ramsay MacDonald.
The question, though, is whether Corbyn’s offer makes more Tory Brexiteers realise that the withdrawal agreement is, for all its flaws, the cleanest Brexit on offer. Given that the Commons won’t let the UK leave without a deal, if May’s deal is defeated again when she brings it back with whatever change she can secure to the backstop, then she’ll have little choice but to accept Corbyn’s offer.