Ex-chancellor Sajid Javid was reported to be incandescent with rage at a briefing to the Sunday Times newspaper that he was incompetent and should not replace Kwasi Kwarteng at the Treasury.
Mr Stein is considered an ally of Jeremy Hunt, who ultimately got the job – having previously worked for Mr Hunt’s 2019 leadership campaign.
Mr Javid was lined up to challenge Ms Truss at Prime Minister’s Questions on Wednesday, but ultimately did not ask his planned question. The aide was reported to be suspended just minutes before PMQs began.
ITV News reports that Mr Javid had demanded the suspension in exchange for dropping his question to the prime minister – whose leadership is on the ropes.
Mr Stein was Ms Truss’s senior campaign advisor during her Tory leadership bid this year.
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He also previously advised Prince Andrew on media matters.
Downing Street declined to comment on the reports, which first appeared on the BBC and Sky News.
But a No 10 source said: "The prime minister has made very clear to her team that some of the sort of briefings that we have seen about parliamentary colleagues are completely unacceptable and they must stop."
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