World leaders said the deal would prepare the U.K. for an “orderly withdrawal,” according to BBC. While some leaders said it was a sad day for the union, U.K. Prime Minister Theresa May said she was “full of optimism.” She added that the deal “delivered for the British people” and would help get the U.K. “on course for a prosperous future.”

While European Union leaders ultimately gave the deal their blessing, they mostly reacted to the decision on Sunday with dismay, Quartz reported.

German Chancellor Angela Merkel said she felt divided over the deal. “I feel very sad, but at the same time I feel a sense of relief,” she said. Spain’s prime minister Pedro Sánchez said that everyone loses with Brexit, but “especially the U.K.”

But the deal isn’t fully set in stone just yet and will now have to be approved by lawmakers in the U.K. parliament. The deal’s approval by U.K. leaders appears to be uncertain, if unlikely, according to CNN. Politicians on all sides have expressed opposition to it.

Arlene Foster, the leader of the Northern Irish DUP said that her party “will not be able to support” the deal, and her sentiments were echoed by other U.K. politicians.

“What Theresa May has succeeded in doing is putting a proposition on the table which is worse than no deal and worse than staying in the E.U., whatever else is put on the table,” said Nigel Dodds, the deputy leader of the Democratic Unionist Party, according to Quartz. Labour Party leader Jeremy Corbin called May’s deal a “miserable failure of negotiation that leaves us with the worst of all worlds.”

During the summit in Brussels, however, May urged voters on both sides to unite behind the deal because, she said, the British people “do not want to spend any more time arguing about Brexit,” the BBC reported.

May was asked by reporters on Sunday if she would step down as prime minister if her deal flopped. “My focus for the next few weeks is making this deal possible,” she responded. “If people think there’s another negotiation to be done, that’s not the case.”