LATEST: Labour backbenchers plot to drive out Brown

An email will be sent by a group of Labour MPs to colleagues within the next week in the wake of expected drubbings in local and European elections.

Previously loyal Labour MPs are involved in the plot, the Standard has been told. "There is an agreement that emails will be circulated after the election," said one MP.

It came as Mr Brown was warned to assert his authority or risk a full-scale leadership crisis within days. The plea came from loyalists as ministers rallied to prop up the Prime Minister after days of mounting confusion and chaos in the Government.

But on the eve of the elections tomorrow Mr Brown took two heavy blows.

There were rumours Alistair Darling could resign from Government if he is demoted. His spokesman said: "Alistair has no plans to stand down."

The Guardian newspaper publicly withdrew its support from Mr Brown in a scathing editorial, saying it was time for Labour to "cut him loose".

In addition, there were reports rebel backbenchers were actively soliciting names for a letter calling on him to resign in the interests of the party.

Although there is no sign yet of senior Cabinet ministers being willing to muster a delegation telling the Prime Minister his time is up, that could change if next week's reshuffle, intended to stamp his authority on the Government, goes badly wrong.

Health Secretary Alan Johnson is seen by some ministers as a better figure to lead Labour into its most dangerous general election for a generation.

Labour MP John Mann said he hoped Mr Brown would still lead the party to the election. "I hope he will be but to do so he has got to go for it," he said. Former deputy leader Roy Hattersley said: "What he's got to do is really take control, not just appear to take control, not just hope for headlines, but he has to have a reshuffle which shows it's his Government. No compromises, no balance, Gordon Brown the boss."

Lord Falconer said he supported Mr Brown "as we go into an election". The comment implied the senior Blairite could speak out once tomorrow's elections are out of the way.

The crisis deepened yesterday when a series of ministers led by Jacqui Smith announced they were quitting in the reshuffle. Cabinet ministers jockeyed for position, with several insisting they did not want to be moved, including David Miliband and Alan Johnson.

Liberal Democrat leader Nick Clegg said the PM was "in power but not in control". "There's this feeling that people cannot run things because there is this disarray at the centre," he said.

Harriet Harman led a group of ministers who took to the airwaves this morning defending Mr Brown: "He does have a plan. I know there's a sense of frenzy, feverishness and speculation but I can tell you the Government is hard at work making sure we protect people in difficult times."

But the Guardian's pungent editorial wrote off the Prime Minister as a leader without vision or authority. It said: "The truth is that there is no vision from Brown, no plan, no argument for the future and no support. The public see it. His party sees it.

"Labour has a year left before an election; its current leader would waste it. It is time to cut him loose."