Former health secretary Frank Dobson, In an interview to be broadcast on the GMTV Sunday Programme, has called on Tony Blair to resign for the sake of the party.
He said that it would "be better if he went sooner rather than later".
Mr Dobson said: "Frankly the only way to put an end to it is for Tony to resign because we can't make a fresh start until we've got a new leader - whoever it may be."
The situation had led to a "period of uncertainty", he said.
He added: "Well I think that's the problem, the Government urges everybody to do risk assessments these days.
"I think if you'd done a risk assessment of the recent announcement you'd have come to the conclusion there were very substantial risks that were going to be more and more rare as more and more back-biting, more and more back-stabbing, to the disadvantage of the Labour Party and whoever succeeds Tony Blair."
And in a withering attack on former health secretary Alan Milburn, Mr Dobson accused him of "snivelling round behind people's backs".
He accused Mr Milburn, who replaced Mr Dobson in the Department of Health, of making a "terrible mess" of the NHS.
