Sir Keir Starmer has emerged as the clear favourite to succeed Jeremy Corbyn with experts giving him a 72 per cent chance of winning the race.
The shadow Brexit secretary is heads and shoulders above other candidates as the leadership race heats up.
Rebecca Long-Bailey was as high as 52 per cent on the Smarkets exchange shortly after Labour’s calamitous result in the December General Election.
However, she is now down to 14 per cent, ahead of Lisa Nandy (10 per cent) and Jess Phillips (4 per cent).
Emily Thornberry is hoping to gain enough votes to join the race but is seen as a big outsider.
Elsewhere Clive Lewis has abandoned his bid to become Labour leader after acknowledging he could not get the required support from his fellow MPs.
The latest figures showed he had five nominations, still 17 short of the 22 required, and he said he decided to pull out to allow his supporters to back other candidates.
Shadow foreign secretary Emily Thornberry is the only other candidate yet to hit the 22 threshold before the close of nominations on Monday afternoon.
Mr Lewis said: “At this stage, it’s clear that I won’t get on the ballot.
“So, I’m standing aside in the spirit of pluralism, diversity and generosity that I’ve promoted throughout this campaign, so that those who have supported me can recast their nominations.”
Ms Thornberry has until 2.30pm on Monday to secure the 22 nominations from Labour MPs and MEPs needed to go forward to the next stage of the contest.
Four contenders – Sir Keir Starmer, Rebecca Long-Bailey, Lisa Nandy and Jess Phillips – already have the numbers they require to go through.
The latest figures showed Ms Thornberry had 13 nominations.
With a significant number of MPs yet to decide who to back, Ms Thornberry said at the weekend that she was “fairly confident” of making it.
Miliband backs Starmer
Former Labour leader Ed Miliband said he had nominated Sir Keir as the best candidate to “deliver 21st century socialism”, and deputy leadership candidate Angela Rayner for having “an ability to inspire our party and movement”.
In the race for deputy leader, which is running in parallel, two more candidates successfully went through on Monday.
Rosena Allin-Khan and Dawn Butler reached the magic number of 22 with only hours to spare before the deadline.
They join shadow education secretary Ms Rayner and Ian Murray in progressing to the next round of endorsements.
Shadow justice secretary Richard Burgon required three more nominations.
Those who qualify in the two contests then need to get the nominations of 33 local constituency parties or three Labour affiliates, including at least two trade unions, to enter the final postal ballot of party members and registered supporters.
Over the weekend, the left-wing activist group Momentum, which helped propel Mr Corbyn to the leadership in 2015, said it was recommending support for Ms Long-Bailey and Ms Rayner.
It will now ask its members whether they agree with the recommendations, with ballots, consisting of just two questions, to be sent out this week.
The group’s backing for Ms Long-Bailey is unsurprising, given that she has long been the favoured candidate of the left to take on Mr Corbyn’s mantle.
However, many Corbyn-supporting MPs are backing Mr Burgon for deputy rather than Ms Rayner, and Momentum’s support will be a significant boost for her campaign.
Although she already has the support of her close friend Ms Long-Bailey, Ms Rayner is distrusted by some on the left after backing Andy Burnham for leader in 2015 rather than Mr Corbyn.
Reports have suggested some around the Labour leader believe she was responsible for trying to undermine him.