(Bloomberg) -- U.K. Prime Minister Boris Johnson’s Northern Irish allies are warning they will not support his proposed Brexit deal, putting chances of an agreement in fresh doubt.

Despite the progress made between European Union and U.K. negotiators in Brussels on Wednesday, the Democratic Unionist Party, which props up Johnson’s administration, raised a series of concerns on Thursday morning.

The British and European negotiating teams have been working intensively to finalize a legal text in time for EU leaders to sign off at a summit in Brussels starting on Thursday. Hopes rose that an accord was within sight.

Failure to strike an agreement this week would plunge U.K.’s divorce from the EU back into chaos. Johnson has said he would rather rip the country out of the bloc on time on Oct. 31 without a deal than delay exit day again.

Key Developments:

  • DUP issues statement saying it can’t back the deal “as things stand”
  • The pound fell as much as 0.6% on the DUP announcement
  • Summit of EU leaders due to begin in Brussels Thursday
  • Euro-skeptic Tories say they want to support the agreement but need detail

DUP Says No to Draft Plan for Deal (7:49 a.m.)

The chances of a swift Brexit deal received another blow early Thursday. Northern Ireland’s Democratic Unionist Party, which helps prop up Boris Johnson’s minority Conservative government in London, said “as things stand” it will not back the draft agreement. As ever, the key hurdle is how to resolve the future arrangements for the Irish border.

DUP leader Arlene Foster identified three key sticking points preventing her signing up. These were: proposed arrangements for dealing with customs checks on goods crossing the the U.K.-Irish border; the mechanism for giving Northern Irish politicians a veto over those arrangements; and a lack of clarity on how to institute sales tax in the region.

“We have been involved in ongoing discussions with the Government,” Foster said in a joint statement with her colleague Nigel Dodds. “As things stand, we could not support what is being suggested.”

The DUP’s backing is seen as crucial to Johnson’s willingness to sign up to an agreement. He needs the party’s votes in Parliament to maximize his chances of getting a deal ratified in the House of Commons. The DUP said it would continue to work with Johnson to seek an agreement.

Earlier:

A Brexit Deal Is So Close But It Could All Still Go Belly Up

To contact the reporter on this story: Tim Ross in Brussels at tross54@bloomberg.net

To contact the editors responsible for this story: Flavia Krause-Jackson at fjackson@bloomberg.net, Richard Bravo

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