The timetable for electing Ed Miliband’s successor is expected to see the Labour Party’s new leader announced in mid-September.
The party’s ruling national executive committee meets later to make a decision, but sources have suggested that the new leader is set to be announced on September 12.
Balloting is expected to open in mid-August, leaving three months for campaigning by the candidates.
Announcing the new leader on September 12, a day before the TUC Congress opens, would mean he or she would address the Labour Party conference at the end of September already in place.
Another option would be an earlier campaign, with the winner announced in mid-August, or a later date at the end of September.
It is understood that the executive will plump for the September 12 date.
The decision comes as senior Labour figures urged the party not to rush in to electing a new leader following a bruising election defeat, including a near wipeout in its former Scottish strongholds.
Shadow transport secretary Michael Dugher said the party should have a “thorough internal debate” about its future as he launched a strongly-worded attack on Mr Miliband’s leadership.
MP and NEC member Jonathan Ashworth has suggested that the election should take place after the party’s conference in September, allowing candidates to use the platform to make their pitch to members.
A Labour spokesman said the NEC would have “full discretion” in deciding the timetable for the election, taking into account the opinions of members, constituency Labour parties, the shadow cabinet and Parliamentary Labour Party.
Shadow business secretary Chuka Umunna and shadow health minister Liz Kendall have both confirmed they will stand in the election, with others tipped to join the race including shadow education secretary Tristram Hunt, shadow home secretary Yvette Cooper and shadow health secretary Andy Burnham.
Meanwhile, Walthamstow MP Stella Creasy has indicated she is open to putting her name forward for the position of deputy leader of the party - setting up a potential tussle with Tom Watson, the party’s former deputy chairman.
Mr Dugher used a New Statesman interview to say the leadership election should not be rushed.
“I don’t think we should have a coronation,” he said. “It’s perfectly possible for us to chew gum and walk at the same time. We can have a thorough internal debate about our way forward while going after this Tory government.”
His comments came as he launched a stinging attack on Mr Miliband’s inner circle over the party’s “absolutely unforgivable” failure, claiming the former leader was surrounded by “too many pointy-heads and too few street fighters”.
Mr Dugher also hit out at the widely-mocked stunt of carving key pledges into a stone slab, calling it a “12-foot, granite, marble, cock-up”.
Leicester East MP Keith Vaz said the party needed to “ask Britain” about its failings at the election.
He said he had not backed a specific candidate for leader - noting the last time he did that his choice lost - adding he would prefer as long a process as possible.
Speaking to reporters ahead of the meeting, Mr Vaz said: “I think we need to all work together to find out the lessons of why we lost the last election, have a good process that involves as many people as possible and I’m in favour of having as long a process as possible but it’s up to the NEC to decide.”
On whether the party had adopted an approach that was too left-wing, Mr Vaz said: “I think we need to ask the electorate, Members of Parliament and an even an august body like the NEC is the last place to have the answers. The answers lie with the electorate. We need to ask them.”