Pressure was growing against Gordon Brown this afternoon, with reports that the ground is being prepared for a leadership election.
It was reported in London's Evening Standard and Times Online that a revolt could happen at the start of September.
The Foreign Secretary David Miliband, Labour's deputy leader Harriet Harman and the Health Secretary Alan Johnson are named in the reports.
Both reports said that a number of junior ministers are considering standing down before Labour's conference in September.
The Evening Standard quotes an unnamed former minister as saying there "are probably at least 10" who say they'll resign.
The Times quotes a senior Government source as sating: "Only a handful of people in Downing Street are trying to stop anything happening."
The rebels are said to have been encouraged by suggestions of pairing Mr Miliband and Mr Johnson as a "dream ticket".
And the Times site alleges that Ms Harman commented "This is my moment" when watching the scale of Labour's defeat in the Glasgow East by-election on Thursday night.
The Independent today reported that Cabinet attempts to shore up Gordon Brown's crumbling leadership suffered a fresh setback as senior MPs called openly for him to resign.
A "Lancashire plot" against the Prime Minister appeared to be gathering pace as two backbenchers from the North-west of England urged him to step down and a third questioned his survival chances.
Some MPs are also arguing that he should be replaced in spring if Labour's poll ratings have not recovered by the new year. The onslaught sparked fears among Brown allies that the trickle of demands could become a flood before the Labour conference.
Gordon Prentice, the MP for Pendle, broke ranks to call for the Prime Minister to make way for a rival more in tune with voters.
Graham Stringer, MP for Manchester Blackley, has said Labour "could not go on" as it has after its crushing defeat in Glasgow East and called on the Cabinet to consider forcing a leadership challenge.