The party was hit by revelations of infighting and smear campaigns from Gordon Brown’s former special adviser late last week.
The claims prompted Miliband to appear on The Andrew Marr Show yesterday, stating that he had asked the former prime minister to sack his adviser at the time.
Miliband told Marr that McBride "diminished democracy in the eyes of the public", while at the Labour Party Conference ahead of his keynote speech tomorrow.
Nick Laitner, acting head of public affairs at MHP, said that the opposition leader "could not have ignored the issue" despite a desire to focus on policies.
McBride claimed to have leaked stories about Brown's rivals, with former home secretary John Reid among the targets.
Warning that more revelations would emerge from McBride’s serialised book in the coming days, Laitner said: "You can’t ignore this issue; the first or second question being asked of Labour MPs at the moment is about this, so he had to say something to try to shut it down, and that’s something Miliband did relatively well."
The conference kicked off yesterday, with policies aired over the weekend including curbs on non-EU immigration as well as the guaranteed offer of access to childcare for parents of primary school students.
Labour has also asked the Office for Budget Responsibility (OBR), the Government’s spending watchdog, to scrutinise its manifesto pledges.
Singling out the OBR move for particular praise, Laitner said that so far policy announcements had "landed pretty well’ due to them being "clear, straightforward and electorally attractive".
He added that though "conference tittle tattle" had focused on the McBride claims, it was unlikely to obscure upcoming policy or impact on Labour in the long run.
Connect Communications founder Gill Morris agreed, but added that Miliband still had a lot to do before the conference closed.
"The focus is to get confidence back in Miliband, and it all depends upon what happens with his speech tomorrow," she said.
"There is still a real hunger for policy, and he needs to be very clear in his messaging, and be seen as a leader."