Both Ireland and Spain are starting to say the Brexit negotiations could well spill beyond this week and go right down to the wire at the end of the month.

Irish Foreign Minister Simon Coveney said late Monday it was "too early to say if it is possible to get a breakthrough this week or whether it will move into next week."

At the EU foreign ministers meeting in Luxembourg, Spanish Foreign Minister Josep Borrell said "You know in Europe, we always take decisions on the edge of the precipice, on the edge of the cliff."

Borrell added that "even when the last minute comes, then we stop the watch and say that we need technically more time to fulfill all the requirements, all the last minute requirements."

Originally, this week was seen as the do-or-die week, with a two-day EU summit starting Thursday and a special U.K. House of Commons debate slated for Saturday.