Here we go again with a Prime Minister sending out misleading messages about a negotiation with the EU, which might sound good now but lines up further problems to come. Not only unrealistic, but bad for UK - would give us 10 months to decide many years of future economic policy
And yes a deal with the EU will hamper a US deal. Ask their negotiators. Now this may all be irrelevant to the election, but reality denial has been a major problem in Brexit so far.
Could the next interviewer of the PM please ask him to name a deal the EU has concluded in 10 months. Also which regulations he wishes to align with the EU and which he doesn't. Also whether he will choose EU or US food standards.
Setting unrealistic negotiating deadlines and expectations is just a recipe for failure. Either a GB no deal in 12 months, or more likely 2 year extension, or a very bad EU dictated deal spun as a victory. Still, the PM has form in spinning EU wins as his success.
