The Northern Ireland Office minister Steve Baker says the Prime Minister's Northern Ireland Protocol deal, could have a "really fantastic" outcome.
The arch-Brexiteer was asked whether he would support the deal as he left 10 Downing Street on Monday afternoon.
Mr Baker told broadcasters: "I can only say this: that the Prime Minister is on the cusp of securing a really fantastic result for everyone involved."
The Prime Minister is meeting European Commission president in Windsor, Berkshire, to discuss a “range of complex challenges” around the Northern Ireland Protocol.
The Prime Minister is meeting Ursula von der Leyen at the Fairmont Hotel in Windsor Park before the European Commission President goes on to meet the King.
No 10 raised the prospect that the talks could produce a breakthrough moment after months of negotiations with Brussels about fixing the protocol.
Conservative Brexiteer Jacob Rees-Mogg put Mr Sunak on notice of a possible Tory revolt if the DUP does not support the deal, despite major concessions expected from the EU.
The former Cabinet minister told GB News: "It will all depend on the DUP. If the DUP are against it, I think there will be quite a significant number of Conservatives who are unhappy."
He said that the position of Boris Johnson, who he described as the "biggest figure in UK politics", will be "fundamental".
"So, if the DUP doesn't think that it meets its test, that will be very influential among Conservative MPs," Mr Rees-Mogg added to ITV's Good Morning Britain.
"I'm afraid with all the EU deals the devil is in the detail, so when people say 'we need to see the legal text', they are not larking about, they really want to see it to understand what the effect is."
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