John Prescott led a backlash against Cabinet plotters yesterday, saying that none had the skills or experience to rival Gordon Brown, while the Prime Minister’s allies gave warning that he would sack disloyal ministers.

Downing Street sought to restore discipline after the loss of Glasgow East, Labour’s 25th-safest seat, led to renewed questions over Mr Brown’s leadership.

Cabinet ministers gave Mr Brown a two-month deadline to restore some of Labour’s lost poll ratings or face a ministerial revolt after the defeat, the latest in a series of electoral humiliations since May.

Jack Straw was forced yesterday to disown Labour MPs plotting to install him as a caretaker leader this autumn. The Justice Secretary issued a statement after reports that one of his allies had been collecting names of MPs prepared to join a coup against Mr Brown. George Howarth, a former minister and close ally of both Mr Straw and Tony Blair, told The Sunday Times that Labour MPs needed to “think long and hard” about the leadership. He denied that he had been canvassing support for a challenge on behalf of Mr Straw.

In a statement the Justice Secretary said it would be a “big mistake” for the party to ditch Mr Brown. “I am absolutely convinced that Gordon Brown is the right man to be leading the Labour Party,” he said.

He added: “It would be a big mistake for the Labour Party to now turn in on itself and indulge in a summer of introspection.”

Mr Brown’s supporters remain angry at Mr Straw, however. One loyalist said that he had reported that Mr Howarth had been collecting names before the Glasgow East by-election. He named a number of other Labour MPs, all close to Mr Straw, suspected of plotting against him.

The Justice Secretary was asked by at least one Cabinet minister to tell Mr Brown to quit after Labour’s worse than expected showing in the local elections, The Times has learnt. Although he refused to do so, Mr Straw’s relations with 10 Downing Street have deteriorated. Senior figures in No 10 believe that he can no longer be trusted to be deployed as a regular media performer explaining government policy. Margaret Beckett, the former Foreign Secretary, is being considered to take over the role.

Mr Brown may also bring back into the Cabinet his long-time ally Nick Brown as Chief Whip, moving Geoff Hoon to Leader of the House in a reshuffle before the Labour Party conference begins on September 20, insiders suggest. Although Mr Hoon is not suspected of plotting, Mr Brown is being urged to get a firmer grip on the Parliamentary Labour Party.

In truth, Mr Brown’s room for manoeuvre is limited by his weakened position. Few now expect, for example, that he will be bold enough to sack or sideline Alistair Darling, his Chancellor. Easier targets include Des Browne, Ruth Kelly and Paul Murphy.

Despite the threat of a reshuffle senior ministers continued to voice doubts over Mr Brown’s leadership yesterday and to jockey for position. One is said to have sent colleagues a text reading: “That’s it, the wheels of the bus have just fallen off.”

Friends of James Purnell confirmed that he would not stand against David Miliband while a well-placed source suggested that Alan Johnson may be willing to forge a “dream ticket” with the Foreign Secretary.

However, Mr Prescott, the former deputy leader, appealed to Labour MPs to “take a break from feeding Westminster gossip and hostile press prattle” and warned would-be Cabinet assassins to draw back. “We have, undoubtedly, some very talented men and women. But, with respect, none of them at the present moment has anywhere near the skills and experience, nationally and internationally, to lead this great party and country as we tackle these unprecedented major global problems,” he said.

Geraldine Smith, MP for Morecambe and Lundesdale, said that a change of leader would be absolute suicide and called on Mr Brown to reshuffle any plotters out of the Cabinet.

“All this leadership challenge is absolute nonsense. Who are these spineless individuals who are talking about getting rid of the Prime Minister?” she asked. “If they haven’t even got the guts to to say who they are then I do not think we should take that very seriously.”

That message was reinforced by Ed Balls, the Schools Secretary, and Mr Brown’s closest Cabinet ally, who urged his colleagues not to have a public row. “We have got to show the strength, the discipline, the backbone as a political party to do what the public wants.

“I think there is a lot more that we need to do to get out and show to the public that we are doing, we are acting,” he told Radio 4. “Gordon Brown is resolute and determined to do that; the Cabinet is behind him. “In my view, it is hard for the Conservatives to win this election, but Labour can win it or lose it. It is up to us, and if we do the right things and stick together I believe we can win the next election.”

A senior Labour figure plotting to oust Mr Brown told The Times that he was content to wait for MPs to reflect on their situation over the summer months. “I think that they will reach the same conclusion: this man is a loser, not a winner.”

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