Brexit Secretary David Davis is embarking on a fresh round of negotiations on Britain's EU withdrawal in an attempt to break the deadlock in the stalled talks process.
His fourth set of talks in Brussels with the EU's chief negotiator Michel Barnier comes after Theresa May sought to map out the way forward in a keynote speech in Florence on Friday.
The Prime Minister offered to continue paying into EU coffers during a two-year transition after Britain leaves in 2019 to ensure the bloc is not left with a budget black hole.
However she appeared to be struggling to maintain unity at home with reports of angry clashes behind the scenes between warring Cabinet ministers.
Allies of Chancellor Philip Hammond were reported to have hit back at claims over the weekend that Foreign Secretary Boris Johnson had thwarted his demands for an even longer period of transition.
The Daily Telegraph quoted one unnamed ally of the Chancellor as saying that he was simply being "pragmatic" about the difficulties involved in leaving the EU while Mr Johnson was "talking tough for the sake of it".
"The bottom line is that this is not going to be easy, something that's over-looked by simple-minded Brexiteers like Boris. When it comes down to practicalities, it may well take longer," the ally was quoted as saying.
Mr Johnson had already infuriated some ministers with the publication of his own 4,000-word blueprint for Brexit in the run-up to Mrs May's speech.
Mr Davis denied that the policy had changed as a result of the Foreign Secretary's intervention, saying: "The simple truth is Boris signed up to this."
However the continued infighting among senior ministers is hardly likely to help the Brexit Secretary's cause when it comes to convincing Brussels to accept Mrs May's proposal.
Under her plan, EU nationals will be free to settle in the UK during the transition period while the rights of those living in the country would be written into British law.
Britain and the EU would continue to enjoy the same access to each other's markets while the Prime Minister also held out the prospect of a comprehensive new treaty on future security co-operation.
Mr Davis confirmed the UK would pay in "roughly" £10 billion a year during the transition - although he played down claims that the final "divorce bill" once pensions and other liabilities were taken into account could be £40 billion.
With the clock ticking on the talks, ministers hope the offer will be sufficient to persuade the EU side to move to the second phase of the negotiations on the future relationship between the UK and the remaining 27 - including a free trade deal.
But while Mr Barnier has welcomed the "constructive spirit" of Mrs May's speech, he made clear that the EU side would need to study the proposals in more detail before reaching a verdict.
He also said that greater clarity was needed from the UK on its plans for the border with Ireland following Brexit - another key issue which the EU wants to see resolved before moving to phase two.
The issue will be high on the agenda when Theresa May holds talks in Downing Street with Irish premier Leo Varadkar in her first meeting with an EU leader since the Florence speech.