The Prime Minister suggested it would be “daft” to move Mr Brown.

His decision to remove any question over the future of Mr Brown was a break with the usual protocol that prime ministers do not talk about the composition of their Cabinet until they are safely re-elected.

But with the economy, and their attack on the Conservative economic plans, now so vital to their campaign for re-election Mr Blair, Mr Brown and their chief strategists agreed that a public assurance was needed to prevent all their press conferences and interviews being derailed by questions about Mr Brown’s position.

It means Mr Brown will be in pole position to take over when Mr Blair fulfils his promise to stand down during the next Parliament. The warmth of his words indicated Mr Blair would back him when the time came.

At the first election press conference both men staged an obvious show of harmony that reflected the reality that Mr Brown and his team are now integrally involved in the campaign. The double act approach will continue today when Mr Blair and Mr Brown unveil a new economic poster campaign.

The show of unity between Mr Blair and Mr Brown prompted amusement at Westminster where talk of ever-worsening relations between the two has dominated the politics of the last few years.

The Times understands that both Douglas Alexander, the Brownite Trade Minister who was in charge of election planning in 2001, and Ed Balls, Mr Blair’s former economic adviser, are now on the campaign strategy committee that is guiding Labour’s campaign efforts.

The Blair-Brown attack on the Conservatives came after Michael Howard enthused Conservative MPs with a spirited attack on the Prime Minister in the last Question Time before the poll.

Labour’s manifesto, which was agreed last night at a joint meeting of the Cabinet and the national executive, is dominated by the economy.

The document, to be unveiled next week, will include a pledge not to put up the top or basic rate of tax, although there will be no commitment on national insurance. Mr Blair suggested no new direct taxes were planned for the next Parliament, saying: “The tax we have now is sufficent to pay for the forward plans.”

It will also include a pledge to extend the New Deal programme designed to get the long-term unemployed off benefit and into work, while tightening the benefit sanctions against people who refuse to take job or training offers. Mr Brown and Mr Blair insisted that the economy was at risk from Conservative plans. “So between now and the election we will expose the reality of the economic future offered by the Conservatives and we will be making this the central issue of the election campaign.”

He claimed the Tories were attempting to keep the economy off the election agenda. “It was extraordinary that yesterday the Conservatives made barely a mention of the economy,” he said.

“Their strategy is to avoid debate and discussion on it and avoid the difficult questions that expose the incoherence of their policy.”

Mr Brown, throughout a 75-minute press conference, returned to Labour’s central charge that the Tories would threaten the economy with their £35 billion of “spending cuts” in Labour’s published plans.

The fundamental question at this election is how can you put the party that has been wrong on every major economic decision in the last eight years in charge of the economy for the next five years?

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