Sajid Javid has resigned as chancellor as Boris Johnson carries his cabinet reshuffle.
Mr Javid rejected an order to fire his team of aides, saying “no self-respecting minister” could accept such a condition.
He had been due to deliver his first Budget in four weeks’ time.
The former home secretary was appointed chancellor by Mr Johnson when he became prime minister in July.
His resignation follows rumours of tensions between Mr Javid and the prime minister’s senior adviser Dominic Cummings.