Such a vote would rule out a hard Brexit and allow Remainer MPs a far more influential role in the terms and conditions of the exit deal.
Yesterday the House of Lords approved an amendment to the EU Withdrawal Bill which granted Parliament far more power regarding the final exit deal, with the amendment passing with a huge majority of 119.
The bill will now be sent back to the House of Commons where another vote will take place on Wednesday evening, with Mrs May fighting to convince rebel MPs led by Dominic Grieve to support the Government and reject the amendment.
Yesterday the Department for Exiting the European Union laid out Mrs May’s plans to “overturn the Lords’ decision” on Wednesday, following a week of confusion regarding what Mrs May offered rebel MPs to avoid a Commons defeat last week.
Brexit live: Theresa May has 36 hours to stave off a House of Commons defeat
A spokeswoman for DExEU said: “We cannot accept this amendment. Agreeing to amendable motions would allow Parliament to direct Government on its approach to exiting the EU and so does not meet the reasonable tests set out by the Prime Minister and Brexit Secretary last week.
“However, we are pleased that the Lords have adopted the vast majority of the Government’s amendment tabled last week.
“We will seek to overturn the Lords’ decision when the Bill returns to the House of Commons on Wednesday.”
This is a live blog. See below for breaking news and Brexit updates.
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1.40pm – Verhofstadt speaks out
More detail from Mr Verhofstadt’s talk in Vienna earlier.
The influential MEP joined Mr Barnier to offer opinion on a potential UK-EU security partnership to the European Union Agency for Fundamental Rights.
Referring to the treatment of the 1.24 million British citizens living on the Continent, Mr Verhfostadt said: “I am far from happy concerning the treatment of UK citizens in the EU27.
“We will remain very vigilant on this issue. As we will also on the so-called movement question – ensuring the UK citizens in the EU27 can still exercise their right to free movement within the Union after Brexit.”
12.40pm – Poll shows support for united Ireland
A new poll has shown a surge of support for a united Ireland.
A new poll by Lord Ashcroft Polls has revealed 44 percent of Northern Irish residents would vote in favour of quitting the UK and joining the Republic if a referendum was held tomorrow.
Forty-nine percent of respondents said they would vote to stay in the UK while seven percent said they did not know how they would vote.
Ironically, for the ultra-unionist DUP, who were the only major Northern Irish party to campaign for Leave, it appears their support for Brexit has actually contributed to a rise in support their Doomsday Scenario: the reunification of Ireland.
12.15pm – Barrier admits UK could keep access to Galileo
The UK could access the European Union’s Galileo satellite navigation system after Brexit but will no longer be able to work on developing the project, Mr Barnier has said.
Mr Barnier said in Vienna: “There is a way for the UK to be included in a partnership about Galileo as a user of (services) including the PRS.”
He added the issue should be addressed “in the framework of our future strategic partnership with the UK”.
11.30am – Lord Adonis mocks ‘Tory pipsqueak’
Andrew Adonis has taken to Twitter to praise Remainer Lords for pushing the withdrawal bill back to the Commons.
He said: “Lord Hailsham’s speech on parliamentary sovereignty yesterday utterly magisterial.
“When he rounded on a Tory pipsqueak who accused him of disloyalty – ‘We are the High Court of Parliament not party hacks’ – I thought he was going to reach for the black cap and pass the death sentence.”
Brexit news: Theresa May faces a nervy 36 hours as the House of Commons prepares to vote
10.50am – Verhofstadt says ‘best option for UK is in EU’
Guy Verhofstadt is speaking in Vienna. He said the “best option” for the UK is to cancel Brexit.
Tar Verhofstadt said: “The best option is Britain stays in the EU and then the problem is resolved naturally.
“But that’s not what the British people want and we have to respect this.”
10.15am – Juncker to visit Ireland
Jean-Claude Juncker will visit Ireland this week to discuss “Brexit and other issues currently on the European agenda”.
The president of the European Commission will meet Ireland’s taoiseach (prime minister) Leo Varadkar and receive an honorary doctorate from the National University of Ireland.
On Friday he will meet President Michael D Higgins and visit Croke Park, the fourth largest sports stadium in Europe.
9.40am – Barnier demands Brexit realism
Michel Barnier is speaking in Vienna, where he has demanded “more realism” on what is possible after Brexit.
The EU negotiator said the links between the UK and other EU member states was “unprecedented” but said Brexit meant Britain would lose access to some partnerships including the European Arrest Warren.
He said: “This cooperation is both unique and unprecedented and it’s made possible by the trust between member states. This trust does not fall from the sky. There is no magic wand.
“To negotiate an ambitious relationship with the UK, which we all want, we need more realism on what’s possible and what’s not.
“We know that the UK is not ready to accept the free movement of people, the jurisdiction of the ECJ and the charter of fundamental rights. This means that the UK cannot take part in the European Arrest Warrant.”
Brexit news: Theresa May will fight to prevent a Commons rebellion tomorrow night
9.15am – Brexit, what Brexit?
Next week’s EU summit will focus only briefly on Brexit, with member states distracted by a host of issues across the bloc.
An Austrian diplomat told Politico “there are a lot of very divisive things to deal with”, from the US trade war to migration, and Brexit is not expected to lead the agenda.
The diplomat said: “The most important decision for us, and what we are really waiting for, is the decision on what happens on migration/asylum.”
8.45am – Irish border talks to stretch into autumn
Ireland’s foreign minister Simon Coveney has admitted talks on preventing a hard border on the island will probably stretch beyond June.
This month’s EU summit has long been touted as the deadline for border talks but it appears Brussels and Dublin have softened their stance on allowing negotiations to stretch into the autumn.
Border talks have stalled in recent months with Mrs May unable to offer a solution deemed acceptable by Ireland, the EU and hardline Brexiteers in her cabinet.
8:20am – Barnier and Verhofstadt to make Brexit speech
The EU’s chief Brexit negotiator Michel Barnier will make a speech this morning on security in Europe after the UK leaves the bloc.
He will be joined by the European Parliament’s chief Brexit negotiator and noted EU Army supporter Guy Verhofstadt.
The pair will speak in Vienna, Austria at 9am BST.
More to follow…