Updated 10:30 a.m. ET
Discussions of a Brexit deal came to an end early Sunday as European leaders signed off to split from Britain. The deal includes both a "withdrawal agreement," spelling out the terms of the split, and a "political declaration," with plans for the future relationship between the EU and the U.K.
EU President Donald Tusk announced in a tweet that leaders of 27 remaining EU member states "endorsed" the agreement.
"I think we managed to make a diplomatic piece of art," German Chancellor Angela Merkel said of the deal, according to the Associated Press.
The final hurdle in negotiations was cleared on Saturday when Spanish President Pedro Sanchez spoke with EU and U.K. leaders about the future of Gibraltar, the British territory in southern Spain.
"We are going to resolve a conflict that has been going for over 300 years," Sanchez told reporters on Sunday after the agreement.
The withdrawal agreement will head to British Parliament for an approval vote in December, which could determine whether the plan remains intact before Britain exits the European Union.
Under the deal, the U.K. will officially leave the EU on March 29, 2019. It allows the U.K. a 21-month "transition period," remaining under EU regulations until the end of 2020.
Britain is set to face a $50 billion bill to pay as it exits the EU. In addition to these financial commitments, the U.K. will no longer be required to allow EU citizens to live and work within its borders. Many will need to apply or re-apply for new status under U.K. law.
The agreement faces opposition from all sides — both pro-Brexit and pro-EU legislators in the U.K. have qualms with the plan, which took a year and a half to put together.
Jeremy Corbyn, leader of the Labour Party, said in a statement Sunday that it "is the result of a miserable failure of negotiation that leaves us with the worst of all worlds." He said that Labour Party would oppose the deal in Parliament.
But European Commission President Jean-Claude Juncker was clear with reporters after the summit in Brussels on Sunday: "Those who think that, by rejecting the deal, they would get a better deal, will be disappointed," he said, according to Reuters.
Dutch Prime Minister Mark Rutte told reporters, "There is no Plan B."
In a "letter to the nation," released Sunday, British Prime Minister Theresa May wrote, "I will be campaigning with my heart and soul to win that [parliamentary] vote and to deliver this Brexit deal, for the good of our United Kingdom and all of our people."
It's still unclear what's to follow if a vote in British Parliament doesn't set the Brexit plan in motion.