We won't know until we put it on the table and try to persuade the EU it's the best solution. To do that though we get into some difficult territory - e.g. we need reg alignment and probably need to decide on a dispute resolution mechanism which will involve ECJ in some way 1)
There's no indication the cabinet have found consensus on this. That's because it does preempt the future relationship. The UK would have to make hard choices now - if we want a basic FTA we'd have to accept a NI specific deal. Post agreeing a UK backstop that seems unlikely. 2)
The UK is still holding out on the promise that general mutual recognition, articulated in the Mansion House speech, can be a middle way. As the EU scrutiny committee's report on it makes clear this is not going to happen. publications.parliament.uk/pa/cm201719/cm… 3)
So a UK-wide backstop would effectively set at least minimum regulatory alignment as a baseline offer. It's not like either side would be happy with this outcome and there's still plenty to negotiate. But it would be hard to get more access for less alignment. 4)
Ultimately a UK wide backstop requires movement on both sides redlines. The EU faces a choice between single market purity and a workable solution for all communities on the island. The UK faces a choice between it's constitutional integrity and it's ECJ red lines too 5)
Many have argued the EU will never agree. I actually think the biggest obstacle is still an internal one for the UK. The backstop inescapably preempts the future relationship and the UK is in no position to reach consensus on this now (Notwithstanding coming whitepaper) 6)
I don't know how the UK could fudge this decision - some reports have said it wants a time-limited backstop which would maintain the cliff-edge. Whatever it does it needs to produce an alternative backstop because we're going nowhere without one. ends
