Britain's Prime Minister Theresa May will meet EU leaders in Brussels on Tuesday as she tours European capitals seeking help to save her Brexit plan.
"I'm surprised because we had reached an agreement on the 25th of November," he said, dubbing Brexit a "surprise guest" at this week's EU summit
"Notwithstanding that, it would appear that there are problems right at the end of the road," he told the European Parliament in Strasbourg.
"I will see Mrs May this evening and I have to say here ... that the deal we have achieved is the best deal possible, it's the only deal possible," he warned.
"There is no room whatsoever for renegotiation."
May will also meet Donald Tusk head of the European Council, which represents member states in Brussels, and will host emergency Brexit talks on Thursday.
His office said May was expected in Brussels after she visits The Hague for talks with Dutch Prime Minister Mark Rutte and Chancellor Angela Merkel in Berlin.
On Monday, May postponed an attempt to persuade the British parliament to endorse the Brexit withdrawal agreement struck with EU leaders last month.
Now she is back in European capitals trying to salvage the deal by winning "reassurances" that the EU will not seek to impose a backstop clause on the Irish border.