Home Secretary Amber Rudd said ministers would not be intimidated by hard Brexiteers in her own party as cabinet prepares to agree the shape of UK-EU trade and present Brussels with its plan.
"I have a surprise for the Brexiteers, which is the committee that meets in order to help make these decisions is more united than they think," she the Andrew Marr Show.
"We meet in the committee. We meet privately for discussions. I think that we will arrive at something which suits us all.
"There will be choices to be made within that, but we all want the same thing which is to arrive at a deal which works for the UK."
It comes amid reports that disgruntled Tories are manoeuvring to install a “dream team” of the “three Brexiteers” Boris Johnson, Michael Gove and Jacob Rees-Mogg in Downing Street.
Mr Rees-Mogg, who launched an attack on the civil service after leaked analysis showed any Brexit deal would harm the economy, has demanded the resignation of the Prime Minister’s Europe adviser Olly Robbins, the Sunday Times claimed.
Meanwhile, Senior Tory backbencher Bernard Jenkin launched a fresh attack on Chancellor Philip Hammond, accusing him of pursing his own policy and “formenting confusion” by claiming the UK’s relationship with the EU might only change "very modestly" after Brexit.
Writing in The Sunday Telegraph, Mr Jenkin said the Prime Minister “can only command a majority in Parliament on her present policy”.
He added: “Nearly half David Cameron's MPs, voted Leave, despite his patronage and pleadings. There would have been few Remain Tories if he had advocated Leave.
"Her MPs will back her, because we are overwhelmingly at one with the majority of the British people who now want a clean Brexit and an end to the present uncertainty.
"It is time for all her ministers to back her too and to end the confusion they are fomenting in government."
Ms Rudd attempted to clear up some of that confusion over customs arrangements, with the International Trade Secretary Liam Fox last week claiming a customs union was “not possible” despite Mrs May’s claim to be keeping an “open mind” in her Lancaster House speech last year.
The Home Secretary said ministers were committed to getting a deal which would enable Britain to strike free trade deals with other countries while maintaining "frictionless" trade with the EU.
Ms Rudd acknowledged that it would probably involve some form of customs "arrangement" or "partnership" with the EU.
"We a want frictionless trade at the border, we want to make sure that there is no border on the island of Ireland and we want to make sure that we can do trade deals outside of the European Union. That is the deal we are looking for," she said.
"We need to have this wider agreement. I don't know how far that will go over the next few weeks but I hope the Government will be give the space to try and achieve that."
The Home Secretary said Brexit minister Steve Baker, who was forced to apologise to the Commons after giving credence to Mr Rees-Mogg’s attack on the civil service, had had “an interesting week” and said the pair’s claims were “wrong”.
Former cabinet secretary Lord Gus O'Donnell said attacks on the civil service for allegedly sabotaging Brexit are "completely crazy", following claims officials are "fiddling the figures".