It follows denials from senior figures in government after reports that plans for a second referendum are already under way in preparation for parliament’s rejection of the Prime Minister’s Brexit deal.
Updating MPs on difficult talks with EU leaders last week, Mrs May will ask parliamentarians not to “break faith with the British people” by trying to reverse Brexit.
It would be “another vote which would do irreparable damage to the integrity of our politics, because it would say to millions who trusted in democracy that our democracy does not deliver,” she is expected to say.
“Another vote which would likely leave us no further forward than the last. And another vote which would further divide our country at the very moment we should be working to unite it.”
Allies of Theresa May were forced to distance themselves at the weekend from reports they were involved in secret discussions about a new referendum on Brexit.
The Prime Minister’s de facto deputy, David Lidington, and her chief of staff, Gavin Barwell, made clear they are not in favour of a new EU withdrawal vote.
Mr Lidington was reported to have held talks with Labour MPs last week aimed at getting cross-party consensus for a new referendum.
In response, the Cabinet Office minister posted a link on social media to a parliamentary debate in which he said a second referendum would be “divisive not decisive”.
Education Secretary Damian Hinds insisted Cabinet has not discussed a second EU referendum. Mr Hinds said in a TV interview: “No. Government policy couldn’t be clearer. We are here to act on the will of the British people clearly expressed in the referendum.”
But the former universities minister Sam Gyimah, who resigned from government earlier this month to oppose the Prime Minister’s Brexit deal, said “there are conversations happening about a second referendum and a number of other options”.
He said senior figures in Downing Street were speaking to MPs to “find out what the lay of the land is” when Mrs May’s deal is defeated.
The issue of a second referendum provoked an unprecedented row between a current and former prime minister, after Mrs May said Tony Blair’s calls for a second referendum were an “insult to the office he once held”.
Mrs May accused him of “undermining” Brexit negotiations and insisted MPs could not “abdicate responsibility” to deliver Brexit.
Mr Blair hit back, labelling the Prime Minister “irresponsible” for trying to force her deal through in the face of overwhelming opposition and the threat of a no deal Brexit.
He said: “To describe such a course as an insult is a strange description of what would be the opportunity for them to instruct Parliament as to how to proceed.
“Far from being anti-democratic, it would be the opposite – as indeed many senior figures in her party from past and present have been saying.
“What is irresponsible however is to try to steamroller MPs into accepting a deal they genuinely think is a bad one with the threat that if they do not fall into line, the government will have the country crash out without a deal.”
Mr Blair said it was “perfectly clear neither the British people nor their Parliament will unite behind the Prime Minister’s deal”.
He added: “I have always said, and did again in my speech on Friday in London, that I personally sympathise with the PM’s heavy burden in doing her job. I do not disrespect her at all. I understand her frustration.
“But I profoundly believe that the course she is pursuing will not work and is emphatically not in the national interest. And that’s the reason I am speaking out and shall continue to do so.”
In a sign of the chaos within the government as it struggles to find a Brexit outcome that will satisfy all sides, International Trade Secretary Liam Fox indicated he could support a free vote of MPs on competing Brexit options.
Dr Fox told the BBC’s Andrew Marr Show yesterday: “That’s not something we have considered. I have to say, personally, I wouldn’t have a huge problem with Parliament as a whole having a say on what the options were.”
And Mr Hinds also said “there is a value in flushing out what these various different options are” through Commons votes.
With tensions inside the Conservative Party growing in spite of last week’s confidence vote in the Prime Minister, Tory grandee Lord Chris Patten compared hardline Brexit supporters in the party to “rodents”, “bullying fanatics” and “Maoists”.
He said: “It is impossible to get a deal on the European Union and our relationship with it which is both in the national interest and satisfies the Maoists in the Conservative Party.
“They have been working away like rodents in the basement for years trying to nibble away at the foundations of our relationship with Europe.”
Meanwhile, Irish foreign affairs minister Simon Coveney said Brexit could be delayed if the UK came up with a significantly different proposal.
He said: “If there is an entirely new proposal coming from the UK, then I think undoubtedly you would need a lot more time for that to be considered on the EU side and that would probably involve an extension of Article 50, or pulling Article 50 for the moment, but I think that would be a big decision for Britain to make and Theresa May has said that she does not want to do that.”
Labour MP Dame Margaret Beckett, a former foreign secretary and a leading supporter of the People’s Vote campaign, said it was “highly significant … because officials know the prospect of a People’s Vote is being discussed not just in Westminster but in the corridors of Whitehall too.”
Ms Beckett said: “The case for the public being given the final say is becoming so overwhelming that people from all parties and of none now recognise that this is the best way forward for our country.
“There is no deal that can meet all the promises made for it – or one that is as good as the deal we already have in the EU.
“Any effort to force Brexit over the line without checking that it has the continued consent of the British people will only reinforce divisions.”