Steve Richards: The real fun will start after 5 May when the power struggle in each party gets underway

Blair's closest allies have been meeting, so worried are they that his power will drain away

The three main political parties have fought this election campaign in a state of transition. The carefully constructed programmes and the seemingly self- confident pitch of the leaders disguise an acute uncertainty about what will happen after the election. The doubts relate most explosively to the position of Tony Blair who is fighting his last election. But Labour's leaders are not alone in wondering with a nervy intensity what will follow the voters' verdict.

The three main political parties have fought this election campaign in a state of transition. The carefully constructed programmes and the seemingly self- confident pitch of the leaders disguise an acute uncertainty about what will happen after the election. The doubts relate most explosively to the position of Tony Blair who is fighting his last election. But Labour's leaders are not alone in wondering with a nervy intensity what will follow the voters' verdict.

The Liberal Democrats have clung to their opposition to the war against Iraq as their most distinctive selling point. But a party that relies on one issue will not flourish for long. Once the election is safely over, the party will have the chance to debate the radical proposals put forward by some of its more daring thinkers in the so-called Orange Book mistakenly launched at their pre-election conference last autumn. Will the Liberal Democrats support sweeping reforms of the public services or remain attached to more orthodox solutions? An almighty row was suppressed last autumn. It can start on Friday.

For the second successive election, the Conservatives have put forward a programme that conveniently avoids the big arguments. Until Thursday, they are in favour of higher public spending, tax cuts, and they support the war against Iraq on the unlawful grounds of regime change while condemning Tony Blair for going to war illegally.

After the last two elections, the Tories were too depleted and demoralised to debate their future. On Friday, an important row will almost certainly erupt over whether they lost for being too right-wing or because they were not right-wing enough. Until this debate is resolved, the Conservatives will continue to lose elections.

For Labour, the sense of transition has been most vividly obvious and yet typically complex. The revival of the Blair/Brown relationship has been the most striking development of the entire campaign. It changes everything in a way that is still underestimated. Last autumn, Mr Brown was placed on the margins as Mr Blair declared that he planned to serve another full term with his close ally, Alan Milburn, by his side.

In a dramatic twist, Mr Brown's popularity and the strength of the economy brought him back to the centre of Labour's campaign. Only five weeks ago, some were still speculating that Mr Blair would sack him as Chancellor. Now Mr Brown is stronger than he has ever been since Mr Blair became leader in 1994. This was not what Mr Blair envisaged when he returned from his summer holidays last year, resolved to take on his Chancellor.

Here are some fresh bits of information that demonstrate why the recent revival of Mr Brown changes everything. Contrary to reports, Mr Blair and Mr Brown have had no discussions over the Cabinet reshuffle. Mr Brown will not seek frantic last- minute talks with Mr Blair to secure ministerial appointments for "Brownites". He is no longer interested in angrily fighting for one faction, with Mr Blair resisting or agreeing reluctantly. He has a different and grander ambition now.

When Mr Brown was in a weaker position, he used to bully Mr Blair into delivering what he wanted. Now he feels strong enough to assume that Mr Blair will act in a conciliatory manner without a bitter battle. Similarly, there has been no "deal" over the leadership. As far as Mr Brown is concerned, there is no need for one. For once, the changed dynamics of their relationship have been played out in public. There will be no more behind-the-scenes negotiations where the two of them emerge with different interpretations over what has been agreed.

The only "negotiations" between the two have related to the nature of the current campaign. Mr Brown's fury during the second term related often to strategic differences rather than ideological ones, in particular his concern that Mr Blair preferred to erect dividing lines with his own party rather than the Conservatives. Once Mr Blair had agreed to fight the election on the economy and the differences with Michael Howard, Mr Brown was back on board.

Some of Mr Blair's closest ministerial allies are so worried that power will drain away from the Prime Minister that they met on the Sunday before last with a single question on their agenda: How do we buttress Tony's position after 5 May? They were not entirely sure of the answer.

But they are also lapsing into the pre-election assumptions that battles between Blairites and Brownites will recommence on the old basis. This ignores Mr Brown's determination to take over a unified Cabinet, and his hope that Mr Blair will help to bring this about. As one example of this determination, Mr Brown has expressed his support during the campaign for the public service reforms that Mr Blair seeks to implement. He did so most expansively at yesterday's press conference. I am told Mr Brown will not renege on this support. If Mr Blair attempts to go beyond these, and expand the market-based reforms, he will oppose them, but he will back the policies outlined in the manifesto.

It is also in Tony Blair's interests that the transition is smooth and does not divide an already fragile Labour Party. The Conservatives have never recovered from the fall of Margaret Thatcher, and, oddly, nor has the reputation of the lady herself. She is now often blamed for her party's decline. Mr Blair will not want to go down in history as another election winner who made his party unelectable. I suspect Mr Blair will quickly discover that it is to his own, and his party's, benefit to announce a more detailed timetable as to when he will stand down, thereby ending the speculation about his future that will begin on 6 May.

In the meantime, Mr Brown plans to be on his best behaviour. But he will behave himself knowing that he has acquired a nuclear option. The Chancellor was never going to mount a divisive leadership challenge in a pre-election year. In contrast, over the next year or so he would have the political space to mount a challenge. I am told emphatically that Mr Brown will not do so. He is obsessed by the importance of maintaining unity. But it is there in the background, the nuclear deterrent that he hopes will focus minds in Downing Street.

There is another day or so of intense campaigning in which the real and important differences between the parties will matter. On Friday, the differences within the parties will matter more.

s.richards@independent.co.uk