Senior Labour figures have traded blows amid an increasingly bitter row over the future direction of the party.
Former deputy prime minister Lord Prescott said ex-foreign secretary David Miliband should "shut up" and stop "telling us what to do".
The peer also urged Alastair Campbell to "stay at home" after the former Downing Street spin chief warned he would try to unseat any leader who did not look as if they could win by 2018. Mr Campbell retorted that Lord Prescott was lapsing into his "comfort zone".
The brutal slapdowns came as MPs continued to nominate potential successors to Ed Miliband.
Shadow health secretary Andy Burnham now has 62 backers while fellow frontbenchers Yvette Cooper and Liz Kendall have 51 and 37 respectively.
Left-wing candidate Jeremy Corbyn, with 14, and Mary Creagh, with eight, are still well short of the 35 supporters needed to feature in the final ballot of members.
Nominations close on Monday.
Meanwhile, backbencher John Healey has pulled out of the deputy leadership race saying he wanted to make more space for other contenders.
Only Tom Watson and Caroline Flint have so far reached the nomination threshold, and despite having gained 20 endorsements Mr Healey told the Huffington Post website he was determined to "give more of the other candidates the chance to make the cut".
Writing on his blog, Mr Campbell said: "I like Ed personally but I am afraid the many among the public never saw him as a Prime Minister and though he campaigned well we never got the right economic or electoral strategy in place.
"A good campaign cannot be called a good campaign without a good strategy.
"I will vote for somebody, of course, but I'm not going to back anybody publicly. Whoever wins I will offer support and advice if it is wanted, as I always have.
"But if in two or three years time it is obvious from all we see and hear from the public that the new leader is not winning, and it is obvious we are not going to get close to winning an election, I will not bite my tongue and I will encourage others not to bite their tongues and I will happily lead the charge to try to replace whoever is leader."
However, speaking on the BBC's Daily Politics, Lord Prescott said: "Alastair should know better. What does he mean?
"He's going to tell us whether it's alright in three years? It's going to take us more than three years to get this party back into shape, win the election and the trust.
"Does he then come in on these arguments and say 'you've not satisfied my task and I'm now going to attack you?' Come on. Stay at home Alastair."
The jibe drew a sharp response from Mr Campbell, who sent a tweet to his former colleague stating: "It will not take three years to find out if they are up to it. Sad to see you lapsing into comfort zone. Unity around what?"
Turning his fire on David Miliband, who has criticised the party's "backward looking" approach under brother Ed in a series of interviews, Lord Prescott said: "Terrible. He should shut up. Look, we've gone through that period, the Miliband period is now gone. We're not looking to a period where he emerges as another Miliband interpretation.
"Get on with your international job. Don't come over here telling us what to do."
The peer also complained that the field for the leadership election was "too limited", saying the nomination threshold for entering the final ballot should be lower.
"Jeremy Corbyn's on the left. It would be a better debate if we put Jeremy into it. I wanted a big debate," he said.