Gordon Brown has ordered his ministers to be in the country in early September ahead of a planned reshuffle to boost his flagging premiership.

He has told them to be ready for a Cabinet meeting to plan Labour's autumn fightback.

Loyalists want the Prime Minister to use the offer of plum jobs to keep potential troublemakers in line. No decisions have been taken, but some well-placed sources insist that many big names will be on the move.

However, a Labour MP today urged Mr Brown to call a leadership election, to allow the party to choose between his political programme and those of the rivals who are positioning themselves to succeed him.

Gordon Brown is currently on holiday with wife Sarah

John McDonnell said that an election would allow an "open, friendly and democratic" debate on Labour's future and restore the Government's authority.

He said that he would certainly stand in any leadership contest and hoped that others would also do so.

Despite feverish speculation about a possible challenge to Mr Brown's position, most commentators regard a contest as highly unlikely because of rules which require his would-be successor to obtain the support of 20 per cent of the Parliamentary Labour Party - around 70 MPs.

Mr McDonnell, the chairman of the left-leaning Labour Representation Committee, tried to stand against Mr Brown when Tony Blair stood down last year, but was unable to secure enough signatures to get onto the ballot paper.

He told BBC Radio 4's Today programme: 'We have got to address the problem we experienced last year by not having a leadership election and a proper debate about the future of the party.

'Gordon Brown should welcome that. It is not the old politics of John Major saying "Back me or sack me". It is saying "Here is my politics and my ideology. If people have other views, let them name themselves and stand and let's have that debate and that leadership election".'

'We could have a leadership election which is open, friendly and democratic and involves the whole country.'

'I think if we did it in a friendly, open, transparent way, we would gain people's respect, we would restore our authority as a Government.'

Justice Secretary Jack Straw and Chief Whip Geoff Hoon are candidates for promotion, having emerged as the two figures with enough clout to confront the Prime Minister over his future.

Mr Straw, who has been touted as a replacement for Mr Brown, could be made Deputy PM, while former MEP Mr Hoon could be promised the role of Britain's EU Commissioner in Brussels.

But the crucial decision facing the Prime Minister is what to do with David Miliband, who set out his 'manifesto' for fighting the Tories in a newspaper article this week  -  without mentioning Mr Brown.

A well connected MP has revealed there is talk that Chancellor Alistair Darling and Foreign Secretary David Miliband are trading places

Promotion, possibly to Chancellor, will bind him closer and perhaps spike any leadership ambitions.

But it could also show up the Premier's weakness by rewarding disloyalty.

A demotion or sacking, while sending a strong message that treachery will not be
tolerated, could leave Mr Miliband free to pursue Mr Brown's job without ministerial constraint.

After a bruising week, Mr Brown is determined to reassert his authority ahead of the party conference in late September.

His aides believe that talk of a reshuffle may not only inject impetus into his administration but also head off any leadership challenge beforehand.

There are also signs that the pre-Budget Report might be brought forward from November to keep up the momentum as Labour hopes to regain the political initiative.

An 'economic recovery plan' dealing with voters' worries about falling house prices and rising food and fuel bills is likely to be the centrepiece of any Government relaunch discussed next month.

Other announcements could include a windfall tax on energy companies and the watering down of unpopular changes to road tax.

Some Downing Street insiders suggested that a reshuffle may be delayed because Mr Brown is in China for almost a week at the end of August for the closing days of the Olympic Games.

One said: 'There is no Government machinery in place in August to sort out an early reshuffle, especially as the PM is away for several days in Beijing.'

But notes have gone out to ministers' private offices ordering them to be available for Cabinet on Monday, September 8.

Rumours about the reshuffle include that Health Secretary Alan Johnson or Northern Ireland Secretary Shaun Woodward will be given a higher profile on the airwaves as the public face of Government.

Offering promotions to Mr Straw and Mr Hoon may bring them into the fold.

Despite running Mr Brown's leadership campaign, Mr Straw has fallen out of favour after he initially failed to rein in allies touting him as an alternative leader.

Mr Hoon is under pressure for apparently failing to control dissident backbenchers.

The offer of replacing Peter Mandelson in Brussels next year would remove him from the fray at Westminster, while also being a promotion.

Business Secretary John Hutton is known to fancy a move to the Ministry of Defence, but may be kept in his role.

Unions demanded his head, and Mr Brown might not want to be accused of giving Labour's paymasters a scalp.

Yesterday, Mr Hutton grudgingly backed his leader.

Asked if Labour could win a fourth term under Mr Brown, he replied: 'I think we can win the next election.' Only when pressed did he mention the PM.