Boris Johnson will resign as foreign secretary before the weekend if Theresa May won't bow to his Brexit demands.
That's according to the Telegraph, for whom Johnson wrote his explosive Brexit article over the weekend.
May is due to make a landmark speech on Brexit in Florence, outlining her roadmap for the UK's future relationship with the EU.
The paper says that if May opts for a 'soft Brexit', achieved via a 'Swiss-style arranagement' with Brussels, Johnson will have no option but to quit the foreign office.
Under the 'Swiss-style' option, the UK would pay for permanent access to the single market after Brexit.
This would constitute a direct rejection of one of the key conditions outlined by Johnson in his explosive 4,000-word article about Brexit, published by The Telegraph over the weekend.
The article, which has been described by some as a naked power grab, insists that, in Johnson's vision for Brexit "the UK will not pay to access the EU single market."
Johnson has faced intense scrutiny since publishing the article, with suggestions that May was going to rebuke her charismatic but controversial minister for speaking out on Brexit.
Johnson has said he is not going to resign and said the Cabinet is united on Brexit, likening his fellow ministers to "a nest on singing birds".
However the Telegraph claims he has told friends the soft Brexit option would be unconscionable to him.