Sir Keir Starmer has removed his chief of staff as part of a reshuffle of his senior team ahead of a second potential by-election defeat in Labour heartlands.
Morgan McSweeney, 44, has served as a top aide since helping mastermind Sir Keir’s Labour leadership election victory last year.
However, the moderate organiser has now been asked to take on a "strategic role" with less day-to-day influence. It is not immediately clear who will replace him.
The move comes a week after Labour recorded its worst ever by-election result, securing just 691 votes in Chesham & Amersham.
It is feared a similar loss may be on the horizon in next month’s by-election in Batley and Spen. Polls suggest Labour will lose two per cent of their vote share, while the Conservatives will increase theirs by 11 per cent.
Labour has also announced that Sir Keir’s two most senior communications officials, Ben Nunn and Paul Ovenden, are stepping down.
The party has faced pressure to overhaul its leadership since losing the Hartlepool by-election to the Conservatives, who secured a majority of almost 7,000 votes.
Mr McSweeney, a veteran moderate organiser from Ireland, joined the party in 1997 after being inspired by the Good Friday agreement.