The British Prime Minister's office has said Theresa May continues to have full confidence in Foreign Secretary Boris Johnson, after he described proposals for a customs partnership following Brexit as "crazy".
Meanwhile, Mr Johnson made a very public challenge to Mrs May's approach to Brexit when he used an interview with the Daily Mail to warn that the customs partnership option would create a "whole new web of bureaucracy". "She just wants to kick any decisions down the road for as long as she can".
She seems to be headed for deadlock as prominent Brexiteers within her team have rubbished her proposal of a so-called "customs partnership", under which the United Kingdom would collect tariffs on behalf the EU after it has left the union.
The second is for a streamlined customs arrangement now known as "max fac" - maximum facilitation.
The proposals have split May's cabinet of top ministers, and her party, down the middle.
She said her mission in the talks was to build a new, close trading relationship with the European Union, put Britain in full control over its immigration policy and taxpayer spending and build closer ties with the world's emerging economies.
They support the max fac option, which critics say could take years to set up.More news: Peter Crouch reveals what he thinks of this Manchester United side
Theresa May today seeks to break the deadlock in her warring cabinet and party over their differences on Brexit by declaring "trust me to deliver" and vowing: "I will not let you down".
"The Prime Minister asked officials to take forward that work as a priority".
One group will consider a "customs partnership" whereby the United Kingdom would collect tariffs on behalf of the European Union, but would remove the need for new checks at the border.
The House of Lords, sent a clear message to May in a series of votes on the EU withdrawal bill over the last three weeks, challenging her refusal to stay in the customs union and her plan to leave the EU's single market.
"Parliament is finally taking control of Brexit and is seeing off a minority of ideologically driven hard Brexiteers", Conservative lawmaker Anna Soubry said this week on Twitter.
All EU members are part of the customs union which means there are no tariffs on goods transported between member states.
The pressure is rising for Labour to change position.