British Prime Minister Theresa May is facing calls to sack both Boris Johnson and Philip Hammond in order to reassert her authority over the Tory party.
May vowed she would not "hide from a challenge" amid speculation she could carry out a reshuffle of her top team in order to shore up her precarious position.
Pressure mounted from rival wings of the Tory party to axe either the Chancellor or Foreign Secretary in what would be a high-risk move.
But former Cabinet minister Stephen Crabb warned Mrs May not to rush into any reshuffle and said sacking Mr Johnson would deprive her team of a "formidable player".
The Daily Telegraph reported that Mr Johnson would resist any attempt to demote him, leaving Mrs May with little option but to sack him or leave him in post.
The Prime Minister has repeatedly faced questions about whether Mr Johnson - a potential leadership rival - is "unsackable" due to her weakened position after the gamble of a general election backfired, depriving her of a Commons majority.
But asked what she might do with the Foreign Secretary, Mrs May told the Sunday Times: "It has never been my style to hide from a challenge and I'm not going to start now."
Brexit-supporters turned on Chancellor Mr Hammond and his Treasury amid concerns they were making the process of leaving the EU more difficult.
An unnamed Cabinet minister told the Telegraph that Mr Hammond has "completely failed", is "miserable" and "making Brexit hard".
Former deputy prime minister Lord Heseltine joked on Sky News that he would like to move Mr Johnson to "Mongolia, somewhere like that".
But the pro-EU peer acknowledged that sacking the foreign secretary would be a high-risk move because he would not "go quietly".