Labour leadership candidate John McDonnell has pulled out of the race to help fellow left-wing backbencher Diane Abbott get on the ballot paper.
Mr McDonnell had 11 of the 33 nominations needed to enter the final leg of the race, but Diane Abbott had 16. He now wants his votes to go to her.
Labour's acting leader Harriet Harman said she had nominated Ms Abbott because she did not want to see a "men-only" contest. Ed Balls, who has exactly 33 nominations, said anyone wanting to add their name to his list of backers should instead support Ms Abbott.
Meanwhile Andy Burnham is hoping to make it a four-horse race with just hours to go until nominations close.
The shadow health secretary needs the support of two more MPs to join frontbench colleagues David and Ed Miliband and Ed Balls in the final ballot. Allies have expressed confidence that he will collect the 33 nominations required by the deadline of 12.30pm.
Leading the field with 74 nominations is David Miliband, ahead of his brother Ed on 57.