In essence, Mrs. May's proposal would have permitted the UK to follow some EU rules closely, diverge "moderately" from others, and play by very different rules in the rest.

Once again, EU officials have labeled this proposal as "cherry-picking:" on the part of the UK, and said it's not what they have in mind for the post-Brexit EU-UK relationship.

The Ireland-NI border and the jurisdiction of the European Court of Justice are also problematic issues yet to be meaningfully addressed by the UK.

Watch for updates here as discussions continue.