Former Chancellor Philip Hammond is today essentially asking the Prime Minister, who's meeting the Irish Taoiseach Leo Varadkar in a last minute attempt to hammer out a Brexit deal, to think again.
He tells ITV News that while he hopes that Boris Johnson will get a deal "it isn't going to be the deal that he's put on the table".
He says the proposals put forward by Downing Street are old ideas that have already been rejected by Brussels.
I put it to him that he had two years in Government to come up with a deal and that was also rejected, by MPs.
"All of us are repackaging elements that have been looked at before," he concedes.
Asked if Boris Johnson was genuinely trying to get a deal, he said he thinks Mr Johnson is trying but that the people around the PM dion't want a deal.
He wouldn't be drawn on who those individuals might be.
Mr Hammond believes in the absence of a deal, there will be an extension and so he's suggesting going back to the EU with a new plan that would see the UK stay in the EU's Customs Union to protect UK businesses.
That way, tariffs between the Republic of Ireland and Northern Ireland would be avoided, he argues.
It's an idea that would be instantly rejected by those Conservatives who oppose staying in the Customs Union because it would prevent the UK negotiating free trade deals with other countries.
To Brexiters he says "this deal would be one that Britain could terminate at a time of its choosing".
He adds: "A deal has to respect the genuine red lines on both sides."
There are many outcomes in play within the debate over Brexit at the moment.
An election is one that seems certain and he fears the impact of a Conservative Prime Minister campaigning on a 'No Deal' manifesto.
He thinks an extension to Brexit "... will be sought and will be granted."
He hopes the Tory manifesto will commit to a negotiated deal but that the ideas will have to evolve. Hence his intervention today.
He's not willing, at this stage, to vote for a general election.
"I don't want to see the government turned out of office," he says.
He knows that going out to the country without Brexit being dealt with would risk damage from the Brexit Party, which would campaign to leave "no ifs or buts", to coin a phrase.
Mr Hammond was one of the 21 Tory MPs who lost the whip for voting for the Benn Act.
He hints at more rebellion to come, even more cabinet resignations.
"A lot of my colleagues who remain in the Conservative Party would be very uncomfortable if the Prime Minister were to pivot to that (No Deal) position," he warns.
The former Chancellor is proud of leaving a "war chest" in the Treasury.
He's now worried that the spending commitments on police, hospitals and schools would not be as easily deliverable in the event of a no-deal Brexit.
A "double whammy " he calls the squeeze which he says would be caused by bailing out struggling businesses and matching spending commitments.
It's "not safe" to commit money, that he says was set aside to deal with the outcome of a no deal Brexit, on public spending announcements until a negotiated deal can be done.