British Prime Minister Theresa May and her senior ministers will try to hammer out a deal over the government's approach to Brexit when they meet at her country retreat today.
The Brexit sub-committee gathers at Chequers with the government under pressure to spell out in detail what it wants to secure from Brexit talks.
The UK has said it wants a "deep and special" partnership with the EU.
But ministers have been at odds over how closely the EU and UK should align after exit day in March 2019.
The Brexit sub committee includes key figures like Foreign Secretary Boris Johnson and Chancellor Philip Hammond. Mrs May will be hoping to secure sign-off for a key Brexit speech she is expected to give in the coming weeks.
As well as finding agreement within her government, the prime minister will need to convince the EU of her approach.
Documents released on the eve of the Chequers gathering suggest European Commission negotiators will not approve of a UK proposal that seeks to select which EU rules to follow and which to diverge from.
Slides published online by the commission say such an approach would be "not compatible with the principles" set out in the EU's own guidelines and posed a risk to the "proper functioning" of its single market.
Before the final arrangements with the EU kick in, a temporary transition period is planned - although the details have yet to be negotiated.
On Wednesday the UK set out its plans for how this "status quo" transition phase should work.
The document suggests the UK will abide by new EU laws and be involved in talks on future fishing quotas, but will not be able to sign trade deals without the EU's permission.
It also says the period should last as long as it takes to "prepare and implement the new processes and new systems".
Number 10 denied this meant it would be longer than the planned two years.
In other Brexit news, Amnesty International is claiming the government's key EU (Withdrawal) Bill could "significantly reduce existing human rights protections" in the UK.
In its annual report, Amnesty pointed to the decision to exclude the EU's Charter of Fundamental Rights from the bill, which translates EU legislation onto the UK statute book.
The UK government has said human rights will not be jeopardised by Brexit, saying protections in the EU charter will be covered by domestic law.