Emily Thornberry has withdrawn from the contest to become Labour's deputy leader, leaving four candidates in the race to replace Angela Rayner.

Thornberry, who chairs the Commons foreign affairs committee, announced her decision on social media, saying she was "deeply grateful" to Labour members for their support and that it had been "a privilege to take part in this race with such brilliant women." She had secured 13 nominations from Labour MPs, well below the 80 required to progress to the next stage of the contest.

The withdrawal reduces the field to four contenders: Education Secretary Bridget Phillipson, MP Lucy Powell, Bell Ribeiro-Addy and Paula Barker. Phillipson is the clear frontrunner, having attracted the backing of 116 parliamentary colleagues. Powell, who was sacked as Commons leader last week, has 77 nominations. Ribeiro-Addy, the MP for Clapham and Brixton Hill, has 15 nominations and Barker, the Labour MP for Liverpool Wavertree, has 14.

Candidates must reach the threshold of 80 nominations from Labour MPs by 17:00 on Thursday to remain in the contest; those who fail to do so will be required to withdraw. Housing Minister Alison McGovern dropped out of the race on Wednesday after falling short of that mark and publicly backed Phillipson.

The deputy leadership election follows internal party discussions over direction and leadership after Angela Rayner's tenure as deputy leader. The contest has drawn attention to divisions and alliances within the parliamentary party, as potential nominees and endorsers position themselves ahead of the nomination deadline.

Labour MPs have been canvassing colleagues over recent days to secure the 80 nominations needed to reach the next stage, when party members and affiliated organisations will be able to choose from the shortlisted candidates. With the nomination window closing this week, attention has focused on whether Powell can bridge the gap to 80 and whether the other candidates will be able to broaden their support among MPs.

Thornberry's exit narrows the contest but does not eliminate the uncertainty about how the parliamentary nominations will settle ahead of Thursday's deadline. The remaining candidates now intensify efforts to consolidate backing from colleagues and secure a place on the ballot for the party membership vote.