Labour MPs Rebecca Long Bailey, Lisa Nandy and Jess Phillips have secured support to run in the party’s leadership contest.
The MPs for Salford and Eccles, Birmingham Yardley and Wigan join Sir Keir Starmer on the ballot paper to replace Jeremy Corbyn.
Candidates need 22 Labour MPs or MEPs to nominate them before Monday.
Emily Thornberry and Clive Lewis have also declared they are running, with Barry Gardiner considering joining.
However, Ms Thornberry – the shadow foreign secretary – has only secured seven nominations so far, while Mr Lewis – a shadow treasury minister – has four.
There is also a contest to become deputy leader after Tom Watson stepped down in December.
The new leader and deputy leader will be announced on 4 April.
Shadow business minister Mrs Long Bailey has 26 nominations so far.
Her supporters include shadow chancellor John McDonnell, shadow home secretary Diane Abbott and Labour Party chairman Ian Lavery – who had been considering his own run.
Both Ms Phillips and Ms Nandy have 22 nominations.
Ms Phillips has the backing of former Labour ministers Margaret Hodge and Chris Bryant, while Ms Nandy has shadow health secretary Jon Ashworth and former shadow minister Jack Dromey on side.
Ms Nandy later tweeted she was “proud” to have gained support from MPs “representing different parts of the country and different traditions in our movement”.
However, all three candidates are behind the shadow Brexit secretary Sir Keir, who has secured 63 nominations so far – including from the shadow leader of the House Valerie Vaz and shadow Brexit minister Paul Blomfield.