BRUSSELS (AP) — The Latest on Brexit (all times local):

8:10 a.m.

The leaders of British Prime Minister Boris Johnson's key Northern Ireland ally say they can't support the draft Brexit deal struck between the government and the European Union.

Support from the Democratic Unionist Party is key to Johnson's plan to get an agreement approved by parliament. But DUP leader Arlen Foster and the party's parliamentary chief Nigel Dodds say they "could not support what is being suggested on customs and consent issues."

Those arrangements are key to guaranteeing an open border between the U.K.'s Northern Ireland and EU member Ireland — the main obstacle to a Brexit deal.

Without the DUP's support, any deal is unlikely to be ratified by the U.K. Parliament.

Foster and Dodds said they would continue to work with the U.K. government to get a "sensible" deal.

7:30 a.m.

British Prime Minister Boris Johnson and his 27 counterparts from across the European Union are converging on Brussels for a summit they hope will finally lay to rest the acrimony and frustration of a three-year divorce fight.

Yet high anxiety still reigned on Thursday morning with the last outstanding issues of the divorce papers still unclear and Johnson uncertain whether his allies at home will back the compromises he needs to make a deal.

Technical negotiators again went into the night Wednesday to fine tune customs and VAT regulations that will have to regulate trade in goods between the Northern Ireland and Ireland, where the UK and the EU share their only land border.

The summit starts midafternoon and is slated to end some 24 hours later.