Theresa May will be given an opportunity to "update" EU leaders on Brexit before they discuss the situation and "adopt relevant conclusions" in her absence, European Council president Donald Tusk has said.
The British Prime Minister's intervention will come at the end of the working session of the council summit in Brussels on Thursday, and ahead of a press conference by Mr Tusk and European Commission President Jean-Claude Juncker scheduled for 6pm UK time that day.
Taoiseach Leo Varadkar and Mr Juncker spoke by phone this evening.
A statement issued afterwards said they both agreed that the Withdrawal Agreement is a balanced compromise and the best outcome available.
"While they agreed to work to provide reassurance to the UK, the Agreement cannot be reopened or contradicted."
The Taoiseach thanked Mr Juncker for his "continuing support" and said he was looking forward to the European Council meeting tomorrow.
In a letter to EU leaders today, Mr Tusk acknowledged the "seriousness" of the political situation in the UK.
"The intention is that we will listen to the UK Prime Minister's assessment, and later, we will meet as 27 to discuss the matter and adopt relevant conclusions," he wrote.
"As time is running out, we will also discuss the state of preparations for a no-deal scenario."
The remainder of the two-day summit will focus on issues, including the EU's budget for 2021-27, as well as foreign policy issues, including the tension in Ukraine and the rollover of sanctions against Russia.
Mrs May's trip to Brussels comes after her emergency Brexit talks with fellow EU leaders were cut short so she could fight an effort to oust her as Conservative leader.
Mrs May met her Dutch counterpart Mark Rutte in The Hague, and then travelled to Germany to meet Chancellor Angela Merkel on Tuesday.
But her planned trip to Dublin for talks with Taoiseach Leo Varadkar was cancelled because of the confidence vote.
On Tuesday, Mr Tusk stated that the EU 27 wanted to help Mrs May, but said the "question is how", having previously ruled out renegotiating the deal.
Meanwhile, French Foreign Minister Jean-Yves Le Drian warned today that there will be "no renegotiation" of the Brexit deal.
"There were long negotiations lasting several months that ended with a text agreed by both parties, which was to have been submitted yesterday to the British parliament, and which the British prime minister decided to hold back because of lack of support," Mr Le Drian said.