A Brexit deal? Not yet.

Brexit talks continued late into the night, with Donald Tusk, the European Council president, and Boris Johnson, the British prime minister, offering different takes on whether an agreement might be reached.

Little time remains to strike a deal that can be voted on when European heads of state arrive in Brussels today, and then be approved by Britain’s Parliament in a special session on Saturday — if the country is to leave the bloc by Oct. 31, as Mr. Johnson insists will happen.

Progress: Hopes rose as Mr. Tusk said the “basic foundations of an agreement are ready” and President Emmanuel Macron of France voiced optimism as well.

But there were mixed signals, with the leader of Northern Ireland’s Democratic Unionist Party saying there was much work to be done. (Mr. Johnson needs the party’s support to get a deal through Parliament.) Mr. Johnson himself compared the negotiations to climbing Mount Everest, saying the peak was still “shrouded in mist.”