The hangup may be what causes a hard Brexit
If you look at the big picture, negotiators in the EU and UK have done a great job on the meat of a Brexit deal. From all reports, the main parts of the deal are essentially done.
There are two main issues -- European courts and the Irish border -- the courts are thorny but solvable. Ireland issues are threatening to blow the whole thing up.
The FT today wonder whether the Brexit agreement is even the right place to address the Irish border. From the start, the EU insisted on a backstop agreement but there's a good argument that it needs a separate deal. By including it, the situation has become further politicized and it's given the DUP a way to undermine May at a delicate time.
Maybe the way to a deal is to set aside the Irish problem and get on with it. If they decide to take that tactic, it will create some problems for May but it would remove the economic uncertainty (or at least diminish it) and give the pound a lift.
So far however, that idea isn't even on the table.
Right now, the headline that's weighing on the pound is a report that cabinet was told that a Brexit backstop won't get through parliament.
