BRUSSELS - Britain and the European Union sealed a new withdrawal agreement Thursday, on the first day of an EU summit in Brussels, paving the way for Britain's possible exit from the bloc at the end of the month.
But Brexit is far from decided, as British Prime Minister Boris Johnson faces a tough battle to persuade members of Parliament to approve the agreement in a special session scheduled for Saturday.
Expectations of a possible deal at the Brussels summit were low, with apparent wide disagreements earlier in the week. There was palpable shock as
Commission President Jean-Claude Juncker took to the podium to announce the deal.
"We have a deal, and this deal means that there is no need for any kind of prolongation," he told reporters.
Johnson hailed the agreement a Brexit breakthrough.
"I do think this deal represents a very good deal both for the EU and for the U.K., and it's a reasonable, fair outcome," he said. "And of course for us in the U.K., it means that we can deliver a real Brexit that achieves our objectives. And it means that the U.K. leaves whole and entire on Oct. 31. And it means that Northern Ireland and every other part of the U.K. can take part, not just in free trade deals, offering our tariffs and exporting our goods around the world."
Johnson's pledge to leave the EU "do or die" on Oct. 31 may yet fail, as the deal has to be approved in the British and European Parliaments. British MPs will sit in a Saturday session for the first time since the Falklands War in 1982.
WATCH: Brexit Breakthrough, but British MPs Could Torpedo EU Deal
The agreement was sealed, thanks to changes to the Northern Irish backstop clause. The new deal envisages Northern Ireland remaining in the United Kingdom's custom territory. In practice, however, it will follow EU rules, with an effective customs border down the Irish Sea.
That avoids border checks on Northern Ireland. But the Democratic Unionist Party has rejected any deal that treats Northern Ireland differently than the rest of the U.K.
"We believe it is not in the interests of Northern Ireland, either, economically, and I have explained all that around the border, essentially," Arlene Foster, leader of the Democratic Unionist Party, said Thursday. "Not just for regulations, but for goods. We have different VAT [value-added tax] rules, and we have no effective consent over any of those rules."
Democratic Unionist MPs are crucial if Johnson is to get the deal through Parliament. All opposition parties in Britain have indicated they will vote against it.
Juncker warned the EU would not grant any further Brexit extensions, turning up the heat on British lawmakers. In reality, Juncker does not have a say in whether the EU grants Britain a Brexit extension, as this is decided by the heads of state of the other 27 EU members.
Larissa Brunner, an analyst at the European Policy Center in Brussels, says there is growing Brexit fatigue in the EU and a strong desire to push through an orderly Brexit as soon as possible in the face of opposition among British MPs.
"As long as they believe that there's some sort of third option, or a second referendum, another extension, a general election, some sort of better deal, or whatever it is, they do not seem to be willing to vote for the deal that is on the table."
The speed of the agreement in Brussels shows how eager the EU is to move ahead with a smooth Brexit. But there could be plenty more hurdles ahead as Johnson returns to Britain, ready for what's billed as "Super Saturday."