Brexit negotiations are continuing into the night in a fresh push to reach agreement over the Irish border.
Additional wording has been added to reassure the DUP, whose opposition on Monday led to talks breaking down.
UK PM Theresa May could travel to Brussels early on Friday if a deal is reached.
European Council President Donald Tusk is due to make a statement at 0650 GMT, prompting speculation that a deal is close.
What happens to the border between Northern Ireland and the Republic of Ireland has been among the key sticking points in Brexit negotiations.
On Monday, the DUP - whose support the UK prime minister needs to win key votes in Westminster - objected to draft plans drawn up by the UK and the EU.
They included aligning regulations in Northern Ireland with those in the Republic so as to avoid border checks.
The DUP insists it will not accept any agreement in which Northern Ireland was treated differently from the rest of the UK, reports BBC.