Scottish Labour leader Anas Sarwar will call for Sir Keir Starmer to resign, deepening the crisis engulfing his premiership, according to people familiar with the matter.
Sarwar, who has been seen as a Starmer ally, is the most senior Labour figure to date to call for the UK prime minister’s departure.
Sarwar is expected to make a speech at 2.30pm in which he will call for Starmer to stand down.
Labour is expected to fare poorly in May elections in Scotland, Wales, London and parts of England. The party had at one point anticipated victory in the Scottish elections but has been dragged down by Starmer’s unpopularity.
Earlier on Monday, Downing Street director of communications Tim Allan stepped down amid a scandal over the appointment of Lord Peter Mandelson as US ambassador.
Former Number 10 chief of staff Morgan McSweeney also resigned on Sunday, saying he took full responsibility for advising the prime minister to appoint Mandelson as envoy to the US.
Starmer has faced calls to stand down as prime minister in recent days, including from within his own party, as the fallout from the Mandelson revelations has gathered momentum.
He will address Labour MPs on Monday evening in an effort to shore up his position.