Jeremy Corbyn has given his strongest signal yet that Remain would be on the ballot paper in a second referendum.
Speaking exclusively to ITV News, the Labour leader added that he remains determined to mount a no confidence motion against the Prime Minister next week, whether she pulls Tuesday's Brexit vote or not, or even if it fails to get voted through the House of Commons by MPs.
Mr Corbyn said he does not believe Theresa May's Brexit deal will be passed, branding it "ridiculous", and saying that "it's not going to work, everybody knows that".
Watch the interview in full
When questioned by Political Editor Robert Peston on the topic of a second Brexit vote, Mr Corbyn gave his clearest indication yet that Remain would be an option, by saying another referendum would have to be "qualitatively different to the one held before" and that there would "have to be an option there of what's on offer" in terms of a Brexit deal, suggesting the choice would be between that and Remain.
Mr Corbyn continued that a second vote could be held while still respecting the outcome of the June 2016 referendum.
The Conservative Party hit back at Mr Corbyn's comments, saying another referendum "would take us all back to square one".
The Islington North MP added that there remains no clarity on what this Brexit deal could be, since he does not believe that the Prime Minister's deal will get through Parliament.
Should Mrs May's deal be voted down, Mr Corbyn said there could be "a subsequent offer which will come from the EU Commission next weekend".
The 69-year-old added that another referendum was not an "automatic right" and would have to be agreed by Parliament.
Mr Corbyn continued that the original referendum could not be "re-run" as this would be "met with a lot of dismay from a lot of people" who would feel that their original decision was not being accepted, again indicating that a vote would not be a choice between Leave and Remain as it was in June 2017, but between a Brexit deal and Remain.
Mr Corbyn reiterated that his party's top priority in the event of Mrs May's Brexit deal not being voted through the House of Commons, would be a General Election, but admitted that "other options should remain on the table".
Mr Corbyn also told ITV News that his party remains committed to mounting a vote of no confidence against the Prime Minister, whether she pulls Tuesday's vote or not, or if the motion goes ahead and the Brexit deal is voted down by MPs.
Political Robert Peston says Government sources have suggested to him that Tuesday's vote may not go ahead
On Sunday, Brexit Secretary Stephen Barclay insisted the vote would go ahead as planned, telling the Andrew Marr Show: "We've got the vote on Tuesday. There's still two full days of debate."
Asked if the vote was "100% happening" on Tuesday he replied: "It is."
Meanwhile, the Prime Minister has warned Tory would-be rebels and other MPs that the country would be in “uncharted waters” if the deal is rejected.
However, despite the official position, Robert Peston reported that Government sources had told him that Mrs May could pull the vote.
Mr Corbyn also said that Mrs May's Government "has lost the confidence of the House of Commons" after it was forced to it received on the Withdrawal Agreement from Attorney General Geoffrey Cox, following a vote by MPs to find ministers in contempt of Parliament by withholding the information.
Due to this, Mr Corbyn said there must be General Election "so they [the public] can decide who they want to be in Government, and who they want to negotiate on their behalf" with the EU.
Mr Corbyn said a different Brexit deal must "protect rights and conditions" and give the UK "trade access" to the rest of the EU, if the Government cannot achieve this then "they've got to get out of the way, have an election so that it will be a government here that will be serious about those negotiations".
A Labour Government could negotiate a Brexit deal that would be superior to that achieved by the Conservative Party, Mr Corbyn repeatedly told Robert Peston.
"We need to have a Government in this country that invests in all parts of the country.
"Those left behind communities that voted Leave did so for a reason, because they were fed up with the way they were being treated by the economic norms of this country and indeed other places.
"So a Labour government would treat the whole country very differently and our relations with Europe would be serious, sensible, positive but also robust."
While Mr Corbyn suggested his party was united while the Tories were in disarray, one of his frontbenchers, broke party line to call for a People's Vote.
While a People's Vote is the same as the second referendum mooted by Mr Corbyn in his interview, he stuck to the party line of first calling for a General Election if the Brexit deal is voted down, but if one does not happen, then all options would be kept open, including the possibility of a second referendum.
However, shadow sports minister Rosena Allin-Khan told a People's Vote rally that it is "time to take the Brexit decision back to the people".
The Tooting MP was rebuked by Mr Corbyn, who said he would prefer Labour MPs to be "concentrating solely" on defeating Mrs May's Brexit plan on Tuesday.
The Labour leader told Robert Peston he would be discussing the situation with Dr Allin-Khan.