Gordon Brown is under pressure to axe the so-called Scots mafia who dominate his top team of ministers and to promote “English voices” into more high-profile roles.

Amid concern that Labour is risking a landslide general election defeat, Brown is being urged to give key jobs to ministers who can reach out to middle-class voters in England’s marginal seats.

The prime minister is braced for harsh scrutiny about his recent performance as Labour backbenchers return to the Commons tomorrow for the first time since the disastrous Crewe and Nantwich by-election. However, he is expected to avoid an immediate meeting with backbenchers.

Stephen Ladyman, a former roads minister who is MP for Thanet South, a marginal constituency, said: “It is important to recognise that the election is won or lost in England.

“We need to have English voices speaking and giving messages that make sense in English communities.”

His views were echoed by Lindsay Hoyle, the MP for Chorley: “Voters are looking to see a better balance within the cabinet to ensure that all the regions of England are represented.”

Keith Vaz, a member of Labour’s ruling national executive committee and the chairman of the Commons home affairs committee, called for Brown to appoint an English deputy prime minister.

In a speech to Labour activists, Vaz suggested that Jack Straw, the Essex-born justice secretary, should take over full responsibility for domestic and economic policy.

That would mean an effective demotion for Alistair Darling, chancellor of the exchequer and a Scot, who has been accused of failing to understand the concerns of English taxpayers.

Vaz said: “Gordon has proved to me to be very effective. But now he has got a real opportunity to shake up the government. There is one way of proceeding without the necessity of a huge reshuffle. There is a post that is vacant at the moment and that is the post of deputy prime minister.”

Other MPs believe that Alan Johnson, the south London-educated health secretary, and James Purnell, the work and pensions secretary who went to a Home Counties private school, should be given new roles as the English “spokesmen” for the government.

There are four Scots in the cabinet, including Brown and Darling. Douglas Alexander, the international development secretary from Renfrewshire, and Kilwinning’s Des Browne, the defence secretary, are both highly rated by the prime minister, but some English MPs question their ability to communicate with voters south of the border.

A Labour MP, who asked not be named, said: “We live in a world where there is a quota for women MPs and there may soon be quotas for black MPs. Why should there not be quotas for the English too? The Scots mafia have dominated Brown’s team for too long.”

The anti-Scots backlash has been prompted in part by the humiliation of the Crewe by-election where Labour’s campaign was run by a Scot, Steve McCabe, a government whip. He has been criticised for running a negative campaign caricaturing the Conservatives as “toffs” that backfired among English voters.

As rumours continue to swirl about a formal challenge to Brown’s leadership, a leading ally of Tony Blair attacked the prime minister for being too “tentative”.

Writing in today’s Sunday Times, Alan Milburn, the ultra-Blairite former health secretary, says: “For all the blizzard of initiatives that emanate from Whitehall, Labour has yet to develop a coherent post-Blair agenda.”

Milburn criticises Brown’s draft Queen’s speech, the centrepiece of his recent relaunch, and calls for radical tax cuts targeting the low paid.

The former minister concludes with a coded warning that the prime minister’s time is running out. “Change beckons once again,” he says. “After a decade in office the question we have to be able to answer is: what next?”

It is understood that a small group of former Labour ministers are considering drafting a letter urging Brown to give a timetable for his departure. It would be modelled on the open letter sent by supporters of Brown to Blair in 2006 which forced Blair to bring forward his resignation date.

"We would like to do it,” said a former minister. “But we have to test the mood when MPs return to Westminster.”

David Miliband, the foreign secretary and the favourite to succeed Brown as Labour leader, was given a boost yesterday when he received the unexpected backing of John Prescott, the former deputy leader.

“He is quite a brilliant man and he will be one of our leaders,” said Prescott, speaking at the Hay literary festival.

Brown is expected to avoid attending tomorrow’s Commons meeting of the parliamentary Labour party, the first formal gathering of backbenchers since the Crewe disaster.

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