The Irish Prime Minister has postponed a key press conference in Dublin, as "phase one" Brexit negotiations reach a critical stage.
An agreement on the first phase of talks is thought to be about to be struck.
Theresa May is in Brussels trying to finalise the deal ahead of a crucial summit in ten days time.
May has had meetings with the European Commission President Jean-Claude Juncker and Donald Tusk, the president of the EU council.
The UK has set a deadline of this week for an improved offer.
This should give the go-ahead for more talks at an EU leaders' summit on 14-15 of December.
What has the EU said?
Donald Tusk says he is "encouraged by progress" and a deal on phase one issues - Ireland, the "divorce bill" and citizens' rights is "getting closer".
Tusk represents the other 27 EU members. They must all agree before the next phase of talks can begin.
The EU says it will only recommend the start of long-awaited talks about future trade arrangements when it thinks "sufficient progress" has been made on the three "phase one" issues.
What about Ireland?
Progress in other areas has focused attention on the Irish question.
Dublin wants the UK to guarantee there will be no post-Brexit customs checks on its border with Northern Ireland.
Movement of people and goods must not be impacted, it says.
The EU says Dublin must be satisfied that a so-called "hard border" will not be reinstated.
What is the rest of Ireland saying?
DUP leader Arlene Foster has said her party "will not accept any form of regulatory divergence" that separates Northern Ireland from the rest of the UK.
What everyone else is saying
Responding to resports that Northern Ireland could retain what is being termed "regulatory alignment" with the EU, Scottish First Minister Nicola Sturgeon said "there is surely no good practical reason" why other parts of the UK could not do the same.
She also claimed Dublin is "seeking to unilaterally change" the Good Friday Agreement.
That is the peace deal that brought an end to the Troubles in Northern Ireland.
London Mayor Sadiq Khan says special status for Northern Ireland after Brexit could have "huge ramifications for London".
When is the UK due to leave the EU?
In March, 2019.
However, talks have been deadlocked over the three so-called separation issues.