Brussels(ANN)- All 27 members of the European Union (EU) have approved a deal to end the UK’s membership in the bloc, warning that renegotiation was not an option even if the British parliament rejects it.

Addressing a summit in Brussels to formally adopt the Brexit treaty, European Commission President Jean-Claude Juncker hailed the deal, a product of difficult negotiations for nearly two years, as “the best possible” agreement both sides could get and made it clear that the EU was not going to change its “fundamental position” in the future.

“To see a country like Great Britain… leave the EU is not a moment of joy nor of celebration, it’s a sad moment and it’s a tragedy,” he said, calling it a “sad day” in the EU’s history.

EU chief negotiator Michel Barnier said earlier, however, that the partnership was not over.

“This deal is a necessary step to build trust between the UK and the EU, we need to build in the next phase of this unprecedented and ambitious partnership. We will remain allies, partners and friends,” said Barnier.

The agreement now awaits a critical vote in both British and European parliaments.

UK Prime Minister Theresa May had pushed all along to prevent a vote on the final Brexit deal but failed.

“I do think that the British parliament, because this is a wise parliament, will ratify this deal,” Jucker said.

British Members of Parliament (MPs) are expected to assemble in the second week of December and vote on the 585-page legally-binding Withdrawal Agreement, and a 26-page Political Declaration setting that outlines future relationship.

May, who is still dealing with a rebellion in her own party, is yet to command a parliamentary majority to see the deal approved.

She has been under constant attacks over her handling of the Brexit process after an EU referendum in June 2015 forced her predecessor, David Cameron, to quit. Nearly 52 percent of the Britons voted in favor of the divorce during the poll.

After unveiling the deal earlier this month, five of May’s minister handed in their resignations in protests. Disagreements had chased away several other ministers, most notably former Foreign Secretary Boris Johnson.

Renegotiation not an option

There is growing speculation that a no vote would force May back to the negotiating table, something EU leaders said was not likely.

“It will certainly not be renegotiated and there is no leeway,” Austrian Chancellor Sebastian Kurz said of the deal.

Dutch Prime Minister Mark Rutte said the agreement represented “the max” that negotiators could possibly achieve.

Swedish Prime Minister Stefan Löfven did not rule out the possibility of extending the Lisbon Treaty’s  Article 50 process – which gives a 2-year deadline for the divorce to complete.

He also said small tweaks to the text of the agreement were still likely but “major negotiations” in the event of a no vote by UK lawmakers was not an option.