BRUSSELS (AP) – European Council President Donald Tusk says the European Union has approved a Brexit deal with Britain.

Tusk tweeted that 27 EU leaders meeting in Brussels “endorsed the Withdrawal Agreement and Political Declaration on the future EU-UK relations.”

The deal sets out the terms of Britain’s departure on March 29 and sets a framework for future ties.

Now British prime minister Theresa May faces the tough task of selling the deal to a sceptical UK Parliament.

European Commission President Jean-Claude Juncker says it’s a tragedy that Britain is leaving the European Union but that the country is walking away with the best deal it could hope for.

Juncker said that “it’s a sad day,” as he arrived Sunday for an EU summit in Brussels to endorse the Brexit agreement.

He told reporters that the summit “is neither a time of jubilation nor of celebration. It’s a sad moment, and it’s a tragedy.”

Asked whether a better agreement can be found, should the U.K. Parliament reject it, Juncker said: “This is the deal. It’s the best deal possible. The European Union will not change its fundamental position.”

EU27 has endorsed the Withdrawal Agreement and Political Declaration on the future EU-UK relations. — Donald Tusk (@eucopresident) November 25, 2018

Lithuanian President Dalia Grybauskaite says European Union leaders will agree Sunday on the terms of Britain’s departure from the bloc, but that “it is up to Britain what is next.”

Asked at an EU summit Sunday what would happen if the U.K. Parliament rejects the Brexit deal, Grybauskaite said: “it’s not now our concern, it’s a British concern.”

She says several things could happen in that case, including a new referendum on Brexit, new elections in the U.K., or a request to renegotiate the deal with the EU.

Britain leaves on March 29, but future relations and trade will be tackled during a transition period lasting at least until the end of 2020.

Grybauskaite said “the process will still be long.”