Education Secretary Bridget Phillipson and former Commons leader Lucy Powell appear set to face each other in the contest for Labour's deputy leadership after left-wing backbencher Bell Ribeiro-Addy failed to win enough parliamentary nominations by the deadline.

Ribeiro-Addy said on social media that she had not secured the 80 MP nominations required by 17:00 BST on Thursday to progress. "Unfortunately, I have not secured the high number of nominations required to proceed in the deputy leadership contest," she posted. "I am disappointed that the full range of Labour members' views will not be represented on the ballot paper." The result leaves Phillipson and Powell as the only remaining candidates heading into the next stage.

Under the contest rules, contenders must first be nominated by at least 80 Labour MPs. They then need the backing of either 5% of local Labour parties or three Labour-affiliated organisations, such as trade unions, to secure a place on the ballot for the membership. A ballot of party members is expected to open on 8 October and close on 23 October, with the winner due to be announced on 25 October. The remaining candidates are scheduled to take part in hustings during Labour's annual conference in Liverpool at the end of September.

Phillipson emerged as an early frontrunner after securing the required MP support a day before the nomination deadline. She is the only cabinet minister still standing in the race and has attracted backing from MPs seen as loyal to the leadership. Powell, who was reported to be three nominations short by Wednesday evening, appears to have reached the threshold by the close of nominations. Powell was recently removed from her cabinet role in a ministerial reshuffle.

The contest was triggered by the resignation of Angela Rayner, who stepped down after regulators found she had failed to pay sufficient tax on an £800,000 flat in Hove. Rayner had served as deputy prime minister; that governmental post has been given to Justice Secretary David Lammy in the current cabinet. The deputy leader role in Labour, however, is a party office distinct from a government appointment and carries its own mandate. A deputy leader cannot be dismissed by the party leader and typically serves as a key link between the party membership and its leadership while playing a prominent role in election campaigns.

Party figures and commentators say the race could serve as a forum for expressing dissatisfaction with the leadership, potentially drawing attention at the Liverpool conference and among the membership ahead of the ballot. Some senior Labour figures have argued the next deputy should be a woman and drawn from outside London to broaden the party's appeal; others say members may prefer a candidate willing to challenge Sir Keir Starmer, a dynamic that could affect Phillipson's prospects given her cabinet position.

Labour MPs, affiliated organisations and local parties will now turn their attention to the next qualifying threshold: securing the necessary constituency or affiliate backing to reach members' ballots. If both Phillipson and Powell achieve that support, party members will choose between them in what is likely to be a high-profile contest, with the winner taking on a central role in Labour's organisational and electoral strategy ahead of the next general election.