Theresa May is hosting an eight-hour inner Cabinet summit intended to finally thrash out the UK's Brexit objectives after Tory tensions on EU withdrawal rose to the surface again.
The Prime Minister is heading crunch talks with senior ministers at Chequers today (February 22) in a bid to secure a united line on the exit agenda.
The 11-member inner Cabinet Brexit committee will meet at the Prime Minister's country residence to decide a clear negotiating path as talks with Brussels step up a gear.
With the gathering expected to continue late into the evening, May is aiming to get clear consensus on the details of Britain's framework for a future relationship with the EU.
However, there was a setback to May's plans on the eve of the meeting, as the European Commission released a document explicitly rejecting her "three baskets" approach to future regulatory co-operation.
The approach, set out in her speech in Florence in September, envisages different areas in which the UK would either continue with existing regulatory frameworks, operate its own separate rules largely mirroring those in the EU or diverge significantly from the Brussels regime.
But a set of slides setting out the commission's negotiating position stated: "UK views on regulatory issues in the future relationship including [the] 'three basket approach' are not compatible with the principles in the [European Council] guidelines."
British attempts to "cherry-pick" EU rules threaten the integrity of the single market, while efforts to preserve UK influence over EU decision-making after Brexit "risk to unsettle the EU 'ecosystem'," the slides warned.
Meanwhile, Labour announced that Jeremy Corbyn will make a significant speech on Brexit policy on Monday (February 26), in an apparent attempt to steal a march on the Prime Minister, who is expected to use a high-profile address days later to set out her own vision of Britain's "end state" relationship with the EU.
The Chequers meeting comes after leaked negotiating guidelines caused concern among Brexiteers, and the Government was forced to dismiss claims it was seeking a more open-ended transition deal after the UK formally quits the trading bloc in March 2019.
The paper stated the length of the "status quo" transition "should be determined simply by how long it will take to prepare and implement the new processes and new systems that will underpin the future partnership", which "points to a period of around two years".
The transition strategy outlined in the documents has not been agreed by the Cabinet, according to reports in The Daily Telegraph.