It's the Political Declaration, not the backstop, that could scupper Boris

Here’s a negotiating gambit that seldom fails. Make a blatantly outrageous demand, and the other side won’t notice they’ve been stitched up in the rest of the agreement. That’s what Brussels did negotiating the Withdrawal Agreement. The backstop got so much attention that Britain’s commitments in the Political Declaration – wrongly thought of as optional extras – were ignored. Boris Johnson has already revealed his focus in the negotiations is to scrap the backstop, and has said that:

‘No country that values its independence and indeed its self-respect could agree to a treaty which signed away our economic independence and self-government as this backstop does. A time-limit is not enough.. the way to the deal goes by way of the abolition of the backstop.’

Exactly the same can be said of the Political Declaration. But the battle over the Withdrawal Agreement and the backstop have created the mistaken impression that signing the agreement means Britain leaves with a deal.