At an EU summit in Brussels, the Prime Minister will acknowledge the “give and take” by both sides last week to break the deadlock in the negotiations about Britain’s departure from the bloc.
On Friday morning, the two-day gathering of European leaders at the EU Council meeting in Brussels is expected to formally rubber stamp the decision to allow the talks between the British and EU negotiating teams to move on to the crucial second phase early in the New Year.
And over a dinner for the 28 leaders, the Prime Minister is to welcome the progress made so far and express her hopes for reaching a wide-ranging deal setting out a “deep and special partnership” between Britain and the bloc.
A senior Government source said: “She will welcome the recognition that sufficient progress has been made and say she is particularly pleased a fair settlement has been agreed that will guarantee the rights of more than three million EU citizens living in the the UK and more than a million British citizens in Europe so they can go on living their lives as before.”
The source added Mrs May will acknowledge that “reaching the agreement on phase one has required give and take on both sides but a fair settlement has been achieved”.
In the early hours of last Friday morning, the Prime Minister and European Commission President Jean-Claude Juncker came to an accord on the issues of citizens’ rights, the status of the Irish border and Britain’s £39 billion divorce bill to effectively conclude the first phase of the Brexit talks.
And ahead of Thursday’s summit, chief EU negotiator Michel Barnier praised Mrs May for her “courageous and respectable” conduct of the Brexit negotiations so far.
He also insisted there could be “not going back” on the agreements struck so far.
“There will be internal preparatory work that will need to be done with respect to our future relations with the UK,” Mr Barnier added.
Mrs May is due to head to Brussels on Thursday after attending a memorial service at St Paul’s Cathedral in London for the victims of the Grenfell Tower tragedy.
Officials expect her to leave the summit following Thursday’s dinner as the formal decision giving the go-ahead to the second phase of the Brexit negotiations is due to be taken by the leaders of the 27 nations remaining in the EU after the UK quits.
At the European Parliament in Strasbourg on Wednesday, MEPs voted by 556 votes to 62 in favour of negotiations moving on to their second phase.
But amid some heated exchanges in the assembly, Ukip MEP Nigel Farage claimed Mrs May had “given in on virtually everything”.
In a speech to the parliament ahead of the vote, the former Ukip leader told MEPs: “I don’t think I’ve ever heard so little criticism of the United Kingdom in this chamber in all my life, I guess that doesn’t really take much working out does it?”
“Theresa the appeaser has given in on virtually everything.”
“We’re volunteering to go on paying the membership fee, to accepting all the existing rules, all the new rules, we will effectively once the transition is granted have left the European Union at the end of March 2019 in name only.”
It comes after the PM was left reeling by her first major Brexit defeat in the Commons as rebel Tory MPs helped push through a crucial amendment.
MPs voted 309 to 305 in favour of an amendment to the EU Withdrawal Bill.
This dashed Mrs May’s plans for a take-it-or-leave-it final Brexit vote, with MPs now able to suggest new terms of Britain’s EU exit.
And a furious Prime Minister sacked the Tory vice-chairman for siding with the rebels.
BREXIT BETRAYAL: May loses key EU vote as Tory MPs defy Prime Minister in Remainer plot