Turning to the latest in Brexit negotiations, UK Prime Minister Theresa May has rejected a draft treaty by the European Union, that proposes a common regulatory area in Ireland -- post-Brexit. May says the proposal could undermine the constitutional integrity of the UK. However, Michel Barnier, the EU's chief negotiator, said it was necessary.

MICHEL BARNIER EU CHIEF NEGOTIATOR "To maintain full alignment with all rules of the internal market and the customs union which now or in the future support North-South cooperation, the all-island economy and the protection of the Good Friday agreement. This is the backstop solution that we have to put in the withdrawal agreement. It is the only way to guarantee our joint commitments will be upheld in all circumstances as the joint report requires."

According to the draft proposal, the British-ruled territory of Northern Ireland would stay in a customs union with the EU, if no better solution was found. That could obviously get tricky from a governing standpoint. That's why the UK has rejected measures before that would effectively create a border between the two regions. May is set to address the issue to Parliament next Monday.