Labour's ruling body to choose timetable for election to replace leader Jeremy Corbyn
Other factors that could potentially affect the outcome, such as who is eligible to vote, will also be ruled on during the meeting expected to be attended by the outgoing leader in London today.
Related: EXCLUSIVE: Wigan MP Lisa Nandy enters the race to become new Leader of the Labour PartyThe NEC, which includes shadow cabinet members, will also set the "freeze date" for eligibility to vote for those signing up and the cost of becoming a registered supporter - non-party members who can vote in the race.
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Hide AdShadow education secretary Angela Rayner is expected to launch her candidacy for deputy leader in Stockport. It has been anticipated she will support her friend and shadow business secretary Rebecca Long-Bailey for leader.
MPs hoping to take the helm of the party by the end of March have spent the weekend setting out their stalls, with widespread criticism of the scale of Mr Corbyn's radical proposals.
Prominent backbencher Jess Phillips would not commit to re-nationalising all key utilities and said the free broadband proposal was unbelievable.
Shadow Brexit secretary Sir Keir Starmer said Labour had lost the trust of voters who felt the manifesto was "overloaded".
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Hide AdMs Phillips told The Andrew Marr Show she would "wait and see" how Brexit turns out, but hinted a return to the EU would be possible under her leadership.
But when pressed whether she would re-nationalise mail, water and energy, the Birmingham Yardley MP told the BBC show that "we have to make choices".
"Of course have to in the future look to how those services can better serve the public and nationalisation is one of those ways," she said.
"While there are still homeless people literally sleeping outside my office both in London and in Birmingham we have to make the choices that people can trust that we will deliver."
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Hide AdMs Phillips questioned how the free broadband pledge would have been delivered when other public services were crumbling and people cannot get vital social care for their parents.
"While that is the case offering people free broadband was just not believable," she said.
Sir Keir, the current favourite in the race, said Labour lost the public's trust over a lack of clarity on Brexit, anti-Semitism, and a "feeling that the manifesto was overloaded".
But he told Marr that "we shouldn't retreat from the radical" as he outlined his vision for the future.
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Hide AdShadow foreign secretary Emily Thornberry said the "dreadful" electoral result was partly because the manifesto "just wasn't convincing because their was too much in it".
"In the end, we can say until we are blue in the face that there is another way- and there is - but we won't get the opportunity to serve if people don't believe us," she told Sky's Sophy Ridge on Sunday.
Wigan's MP Lisa Nandy also said the main factor in Labour's failure was trust and blamed Mr Corbyn for failing to acknowledge the power of the Prime Minister's Brexit message.
"Trust - trust was the issue, not the radicalism, not the deeper fundamental change we were promising, but trust," she told Ridge.
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Hide AdMs Nandy also criticised the free broadband pledge, telling the Pienaar's Politics on BBC Radio 5 Live that voters cared about the "more pressing issue in their lives" of buses, adding: "It's not about whether you're radical or not, it's about whether you're relevant."
Shadow business secretary Rebecca Long-Bailey, who is the current leadership's favoured candidate, is widely expected to enter the race but is yet to declare.