UK Prime Minister Boris Johnson agreed a draft Brexit deal with the European Union on Thursday.

The agreement sets up a historic vote in the UK Parliament on Saturday.

The prime minister is likely to struggle to pass any deal, after Johnson's governing partner, the Democratic Unionist Party, said it could not back the agreement as it stands.

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LONDON — Boris Johnson has agreed the terms of a Brexit deal, paving the way for a historic vote in the UK Parliament that could finally see the UK leave the European Union.

Negotiators in Brussels worked intensely on Wednesday and Thursday to reach an agreement on a revised version of the withdrawal agreement, set to be put before the Parliament on Saturday.

Both the UK and the EU welcomed the agreement on Thursday.

"Where there is a will, there is a #deal - we have one!" European Commission President Jean-Claude Juncker tweeted.

Speaking alongside Juncker, Johnson described the deal as good for both sides and insisted they would remain "good neighbours" after Brexit.

The focus will now turn to whether Johnson has enough support to pass the deal through Parliament, after Johnson's governing partners rejected the agreement earlier on Thursday.

Read more: What is in Boris Johnson's new Brexit deal with the EU and what does it all mean?



Read more: Boris Johnson's own official government figures shows his Brexit deal will make British people much poorer

The Democratic Unionist Party, which lends the government 10 votes, said it could not support the deal.

"These proposals are not, in our view, beneficial to the economic well-being of Northern Ireland and they undermine the integrity of the Union," a party representative said.

They added that the party "will be unable to support these proposals in Parliament."

The decision to push ahead with a deal without the support of the DUP means Johnson will struggle to secure support in Parliament, despite winning over some members of his own party.

Watch Johnson welcome his deal with the EU:

The self-styled Spartans, a group of 28 Brexit-supporting Conservative MPs who voted against Theresa May's withdrawal plan three times, has indicated that it is willing to back the deal.

Steve Baker, the most prominent member of the group and the chairman of the hardline European Research Group, said he was "hopeful" that Tory MPs could back the deal, and several leading former rebels have already indicated they will back the government.

But Johnson's hopes of success may rest on a handful of Labour MPs in Leave-voting seats, who have said they are willing to back a deal but may decide to vote against Johnson's as they did against May's.

Stephen Kinnock, the Labour MP for Aberavon, previously indicated that he was willing to vote for a Conservative deal but said on Tuesday that the prime minister should table an alternative proposal that could win cross-party backing.

The opposition Labour Party said it would oppose the deal.

"From what we know, it seems the Prime Minister has negotiated an even worse deal than Theresa May's, which was overwhelmingly rejected," the party's leader, Jeremy Corbyn, said.

"These proposals risk triggering a race to the bottom on rights and protections: putting food safety at risk, cutting environmental standards and workers' rights, and opening up our NHS to a takeover by US private corporations.

"This sell-out deal won't bring the country together and should be rejected. The best way to get Brexit sorted is to give the people the final say in a public vote."

Opponents of Brexit said they would continue to fight against any deal.

Read more: Boris Johnson's opponents move to force a 2nd Brexit referendum as hopes for a deal fade

"The fight to stop Brexit is far from over," the leader of the Liberal Democrats, Jo Swinson, said in a statement.

"Boris Johnson's deal would be bad for our economy, bad for our public services, and bad for our environment.

"The next few days will set the direction of our country for generations, and I am more determined than ever to stop Brexit."

What is Johnson's deal?

Johnson and Jean-Claude Juncker, the European Commission president. Getty

The full terms of the draft deal between London and Brussels were published by the EU on Thursday morning.

Under the agreement, the UK would leave the EU and almost entirely cut its existing trade and customs relationships with the bloc.

However, Northern Ireland would retain closer customs links with the EU to prevent the need for a hard border with the Irish Republic.

The agreement is highly controversial and has been rejected by Johnson's Northern Irish governing partners because of fears that Northern Ireland would effectively be kept permanently tied to the EU.

Read more: The pound is surging to a 7-month high after Boris Johnson secured a Brexit deal with the EU

Johnson's opponents in London also fear that the deal could allow the rest of the UK to diverge from EU rules and regulations on labour and environmental protections.

However, they may be assuaged by the outline agreement for the future relationship encouraging the UK to maintain a "level playing field" with the EU.

Regardless of the terms of the deal, increasing numbers of MPs still believe that Brexit can be stopped and want to block the deal to make way for a second referendum.