A Brexit deal has been agreed between UK and EU negotiating teams before a meeting of European leaders in Brussels.
Prime Minister Boris Johnson tweeted: “We’ve got a great new deal that takes back control.”
The two sides have been working on the legal text of a deal, but it will still need the approval of both the UK and European parliaments.
The DUP has cast doubt on its success, saying they still cannot support it.
The Northern Irish party earlier released a statement saying they could not back proposals “as things stand”, and – after the PM’s announcement – said their statement “still stands”.
Mr Johnson’s proposals for a new Brexit deal hinged on getting rid of the controversial backstop – the solution negotiated between Theresa May and the EU to solve issues around the Irish border after the UK leaves.
By removing it, he hoped to secure the support of Brexiteers in his own party and the DUP – which could hold the key to getting the numbers for a successful vote in the Commons.
Mr Juncker’s letter confirmed both the border plans and the political declaration on the future relationship after Brexit had been revised, and agreed by both him and Mr Johnson.
However, it is understood the new plan would see Northern Ireland treated differently from the rest of the UK – something the DUP, among others, has great concerns about.
The DUP has been in a confidence and supply agreement with the Conservative Party since the 2017 election, which, in the past, gave the government a working majority.
But after resignations and the removal of the party whip from more than 20 Tory MPs in recent weeks, Mr Johnson now could face a tough battle to get his deal through Parliament.