Seven days of torture that will sink – or save – Brown's premiership

Gordon Brown's aides believe he needs to endure only one more week of torture over his leadership before the Labour party and the media realise he is staying until the election, and he can then start to be judged fairly alongside David Cameron. But Brown also knows the next few days could be the most perilous for his premiership since he took office in May 2007.

He needs to seize the initiative quickly by resolving sharp differences of view within the cabinet on a full programme of constitutional reform.

He needs to navigate a fraught reshuffle, probably on Friday, that could see changes to the chancellorship and the Home Office, two of three great offices of state.

And he will have to manage a tense party as it goes through a drawn-out 72 hours of escalating panic in the face of crushing reverses in the county council elections on Thursday night and throughout Friday. That panic will reach a crescendo on Sunday night as the European election results trickle through, and Labour faces the prospect of coming fourth behind not just the Conservatives and the Liberal Democrats, but even Ukip.

As one minister said yesterday: "The actual level of the Labour vote will make a massive categorical difference. It depends if it is 15%, 25% and 35%. The actual level makes a world of difference to Gordon and the party's mood."

All the while, Brown will have to show a steadier hand in response to the daily drip of allegations coming out of the Daily Telegraph. He will not want a repeat of yesterday, when the chancellor, Alistair Darling, and Brown both put out statements insisting the Telegraph's latest allegations were wrong, only for the denial to be retracted within two hours.

But the prime minister reckons if he can chart these perilous waters intact, he will be in the clear and can set out what he describes as a national plan for Britain.

On expenses and the constitution, the cabinet will meet tomorrow to discuss a paper that offers a twin-track strategy. Harriet Harman, leader of the house, and Jack Straw, the justice secretary, will propose reforms to strengthen the role of backbenchers in relation to the executive, both through changes to parliament and through a constitutional renewal bill. It will cover the royal prerogative, war-making powers, the attorney general and a new code of conduct for MPs.

There will also be proposals to elect select committee chairs and remove the executive veto over private members' bills, and new powers for backbenchers to put issues to the vote in the Commons. It is likely that a draft House of Lords reform bill will also be published.

Plans are still being discussed for a citizens' summit, a constitutional convention, a panel of outside experts who would look at electoral reform, a bill of rights, and a written constitution.

Brown can probably resolve the differences in the cabinet over constitutional reform, even if there is frustration at the slowness of the government reaction.

The greater problem is the imminent reshuffle. But as one cabinet aide admitted yesterday: "Normally reshuffles are displays of prime ministerial power and patronage, but this could be the opposite. Some ministers could walk out or resign, and then the whole thing unravels."

The betting inside cabinet circles is that the reshuffle will take place on Friday or Saturday between the close of polls and the European election rout. Brown at that point will be on the brink of a disaster, but its full scale will not be known, thus de­stabilising any cabinet members thinking of mounting a coup.

Similarly, those on the backbenches wanting to oust Brown – the most likely course of events – will probably have to raise the standard of rebellion after the polls close on Thursday night, but will not know if the voters have provided them with the ammunition they need. The rebels will have to build momentum over the coming weekend – and all in the face of a display of "prime ministerial power" over his cabinet colleagues.

But that depends on the reshuffle going smoothly.

Some changes will be easy enough. ­Jacqui Smith, the home secretary, looks politically broken and no longer has the stomach to stay in the cabinet after her husband took the hit for the purchase of pornographic videos on expenses. She is probably reconciled to losing her marginal seat. Similarly, Geoff Hoon, the transport secretary, may fear he is expendable.

But axing Hazel Blears, the feisty communities secretary, would be more difficult. She feels aggrieved that she was singled out by Brown for behaving unacceptably over the designation of her second homes when she felt other cabinet ministers had acted similarly. If sacked, she could be a difficult backbench voice.

Even more, Brown is in a dilemma over Darling. He has been a loyal ally for a generation, and taken many hits on behalf of Brown over the last year. But there is dissatisfaction inside No 10 at the way in which Darling fails to attack the Tories convincingly on the economy. Ed Balls, the children's secretary, would be much more aggressive. If Balls returns to the Treasury, Brown would have the figure he most trusts alongside him in the vital 12 months before the election .

The counter-argument is that if Brown wants to fight the next election on the basis that the government steered the economy through the recession, someone will have to explain why it was necessary to remove the chancellor midway through. Equally, Brown will have to explain why Balls, Brown's chief economic adviser at the Treasury during the development of the credit bubble, is the man to take Britain back to economic growth.

At the moment, the chances of Brown surviving look strong. There is an inertia on the backbenches, and a belief bordering on faith that Brown has hit rock bottom, and will again show his extraordinary capacity to survive adversity. But it is going to be a week that will test Brown like never before.