Gordon Brown's leadership has been called into further question by former home secretary Charles Clarke, who warned he had just months to prove himself or he would have to "stand down with honour".
Clarke had already reignited the prospects of a leadership challenge when he warned the Labour Party would not allow the premier to lead them to "utter destruction" at the next election.
In an article for the New Statesman magazine, published on Thursday, Clarke said there was a "deep and widely shared concern" within the party that the government was currently heading for disaster.
But in an interview with the BBC, the former cabinet minister warned Brown he would have to improve or "stand down as prime minister with honour and have a proper leadership election".
Brown had been a "brilliant chancellor" but had not established his political authority, Clarke argued.
It was "entirely possible" for him to "turn it around" but if he failed to do this and then did not resign, the cabinet would have to decide on a course of action.
But he told BBC Radio 4's Today programme that at present there was no "clarity" about how to address the "deep concerns" within the party.
He said: "What I believe is there are two essential possibilities, both of which are perfectly honourable.
"The first is for the performance of the government to improve significantly... or the second is for Gordon Brown to stand down as prime minister with honour and have a proper leadership election to address the proper issues.
"Both of those are perfectly reputable courses of action."
Asked how long Brown had left, he said: "I think it is a question of months really.
"It is a question of seeing how it works forward and whether he can deal with the situation.
"I am personally a sceptic... but I also believe it is entirely possible that he could turn it around.
"What many people will be wanting to see very soon is clarity about how he is actually doing that."
Clarke attacked as "disreputable" Labour MPs who believed the party was heading for defeat but did not believe there was anything they could do about it. This "fatalism" was "very damaging indeed", he added.
Asked what should happen if Brown failed to provide clarity and then failed to resign, Clarke said: "The best for the country would be if Gordon made his own mind up, that is after all what a whole string of national and party leaders have done in past decades - decided that there came a point where it was better for them to go with honour and I think that would be far and away the best.
"In the event that didn't happen, then I think it would be down principally to the cabinet to decide how to proceed and what to do and to do that in an expeditious way."
But he said there was no mood in the cabinet at the moment to do this.
"Many in the cabinet share the view we are in great difficulty and are doubtful about our capacity of how to get out of it. There isn't a view... that they should go and speak to Gordon in the way I have been describing."
Clarke said he was not prepared to be a "stalking horse" against Brown and he would not advise anyone else to do that because party rules regarding it were "very cumbersome" and would lead to "bitter division".
He added: "It would be much better for the party and the country to come to a view about how the change should take place."
Asked what Brown had to do to improve his standing Clarke said: "He has got to establish his authority and set a very clear leadership direction which makes it clear how he sees the issues will be evolved.
"The question is can he get his government team working as a team? Can he establish an economic programme which is about more than relaunches and odd policy initiatives?
"Can he establish a political direction which is very clear to the country about why Labour is in office and what it is seeking to achieve?"
He called on Brown to establish a "sense of decisiveness and clarity".
Clarke insisted his article represented the views of "many, many, many" people who were concerned about Labour's direction.
The article dismissed reports of a "Blairite plot" by supporters of former prime minister Tony Blair to oust Brown from Number 10.
He wrote: "It is inaccurate and misleading to dismiss as some kind of Blairite rump those who fear that Labour's current course will lead to utter destruction at the next general election," he said.
"Similarly, there is no Blairite plot, despite rumours and persistent newspaper reports.
"There is, however, a deep and widely shared concern - which does not derive from ideology - that Labour is destined to disaster if we go on as we are, combined with a determination that we will not permit that to happen."
Following the article but before his radio interview Clarke was criticised by schools secretary Ed Balls and former minister Nigel Griffiths.
Balls, a key ally of Gordon Brown, told GMTV: "It's not the first time Charles has made those kind of comments. I think it's Charles being Charles.
"I don't think that's where the debate will be when we get to the next general election.
"If you go back to 1986 when the economy was in difficulty, there were people saying the same things about Margaret Thatcher but she went on to win the next election.
"What we've got to do is focus on the big issues and the real divides and the real divide is going to be between Labour and Conservative on the big issues facing the future of our country."
Griffiths expressed his dismay at the intervention by Clarke.
He said: "Yet again Charles has diverted attention away from all the positive things our Labour government is doing - like the extra help we are giving to homebuyers, the extra money to pensioners to help with fuel costs, the action taken to freeze petrol duty."
He told BBC Radio 4's Today: "It is not as if Charles has any alternative policies."
He added: "Charles' problem is this is not the first time that he has gone for the old Dad's Army 'We are all doomed' without coming up with any real alternative.
"He sort of lobs a grenade into the party and then backs away and he did have his chance... in 2007 to come up with alternative policies, and he hasn't come up with them."
