Labour MP for Rochdale Simon Danczuk said he "understands" Mr Miliband will be standing down but denied the party was in crisis.
NSPCC chief Peter Wanless may have "been set up to fail" because he has only had six weeks to investigate what happened to crucial documents in an alleged child sex abuse scandal which have been "lost or destroyed".
Simon Danczuk told Good Morning Britain: "I've talked to experts who carry out these types of reviews using digital technology who say you would need about six months to go through 20 years of documents."
Rochdale MP Simon Danczuk has told ITV News the child sexual exploitation report "doesn't go far enough".
Echoing the comments made by Rochdale whistleblower Sara Rowbotham, Mr Danczuk said, "If she says this report doesn't go far enough then that's good enough for me."
He said the report, led by Stockport MP Ann Coffey, was "really attempting to shift the blame away from the perpetrators and away from the police, and towards public opinion."
"There is certainly a need to learn [from abuse cases] across the country as a whole," the MP added.
Rochdale MP Simon Danczuk has said that police in Manchester need to "win the hearts and minds of the victims" if they want to stop sexual abusers repeating their crimes.
Submitting mislaid files on historical child sex abuse at Westminster is "the test of the Home Office's transparency," according to the MP who lead the campaign for the inquiry into allegations of peadophilia at Parliament.
Simon Danczuk told Good Morning Britain failure to hand in the missing files may lead to the Home Office's permanent secretary to be recalled to answer questions from the Home Affairs select committee.
The MP who has led the campaign for an inquiry into allegations of a high-level cover-up of child sex abuse has urged the former High Court judge appointed to oversee the investigation to stand down because she is too closely linked to the establishment.
Baroness Butler-Sloss has been tasked with heading the probe into whether alleged abuse by politicians and other powerful figures in institutions between the 1970s and 1990s was swept under the carpet.
Labour's Simon Danczuk claimed Baroness Butler-Sloss' position was compromised because her late brother, Sir Michael Havers, was attorney general at the time that many of the allegations relate to.
He told the BBC: "We want somebody in the chair that exudes confidence and that's not the case. She is part of the establishment and that raises concerns, and the relationship in terms of her brother, I think, is too close for comfort. I think that's the conclusion most people will reach.
"I think the Government should think again in terms of who they have appointed for this position."
"It beggars belief that that hadn't been considered in the first place," he added.